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EIOHET! 


HISTOLOGY  AND  PHYS. 


CEREBRAL  CONVOLUTIONS. 


POISONS  OE  THE  IN 


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THE  SEGUIN  COLLECTION 

OF   BOOKS  RELATING  TO  THE 

NERVOUS  SYSTEM 

THE  BEQUEST  OF 

EDWARD  C.  SEGUIN,  M.D. 

TO  THE  DEPARTMENT  OF  PATHOLOGY  OF  THE 
COLLEGE  OF  PHYSICIANS  AND  SURGEONS, 
NEW  YORK. 

D  It         "b  L-     This  book  is  not  to   be  removed 

D00K\  ^ 7-~T\b  from  the  Departmentof  Pathology. 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 
Columbia  University  Libraries 


http://www.archive.org/details/physiologyhistolOOrich 


PHYSIOLOGY  AND  HISTOLOGY 


Cerebral  Convolutions 


ALSO, 


POISONS    OF    THE    INTELLECT, 


BY 

CHAS.   R1CHET,   A.M.,   M.D.,    Ph.D., 

(Former  Intern  of  the  Hospital  of  Paris.) 


TRANSLATED    BY 

EDWARD    P.    FOWLER,    M.D. 


NEW    YORK  : 

WM.  WOOD    &    CO.,  27   GREAT    JONES   ST. 

1879. 


Ksi 


Copyright  by 
WILLIAM  WOOD  &  COMPANY 


STEAM   PRESS   OF 

H.  O.  A.  Industrial  Schooi  , 
76TH  St.,  near  Third  Avf. 


MM.   BROCA  and  CHARCOT. 

PROFESSEURS  À  LA  FACULTE'  DE  MEDECINE  DE  PARIS, 

WHO    HAVE   SO   GREATLY    HONORED    FRENCH    SCIENCE    BY   THEIR    MAGNIFICENT 
WORKS   UPON    CEREBRAL   CONVOLUTIONS. 

CHARLES  RICHET, 


WV 


OTHER  WORKS  BY  THE    SAME  AUTHOR. 


i.  Recherches  expérimentales  et  cliniques  sur  la  sensi- 
bilité, in  8vo  (Masson),  1877. 

2.  Les  poisons  de  l'intelligence,  in  i2mo  1  P.  Ollendorf), 
1877. 

3.  Le  somnambulism  provoqué  {Jour,  de  F  anatomic  et  de 
la  physiologie) ,  1877. 

4.  Etude  sur  la  douleur  {Revue  Philosophique),  1877. 

5.  Essai  sur  les  causes  de  degoiit  {Revue  des  Deux  Mondes), 
1877. 

6.  Du  suc  gastrique  chez  l'homme  et  les  animaux,  ses 
propriétés  chimiques  et  physiologiques,  in  8vo  (Germer, 
Baillière  et  Cie.),  1878. 


AUTHOR'S     PREFACE 

TO   THE   TRANSLATION. 


Should  my  work  appear  to  its  readers  in  some  degree 
incomplete,  as  it  certainly  must,  I  will  solicit  indulgence 
upon  the  following  grounds  : 

i st.  That  discoveries  in  cerebral  physiology  succeed 
each  other  with  exceptional  rapidity,  and  any  work  upon 
this  subject,  after  a  few  months  of  existence,  of  course  fails 
to  include  an  important  mass  of  facts  which  each  new  day 
develops. 

2d.  To  fairly  understand  this  department  in  medical 
science,  and  to  be  able  to  explain  it  intelligently,  exacts  a 
familiarity  with  a  greater  number  of  sciences  than  does 
almost  any  other  subject. 

First  of  all,  it  is,  as  a  matter  of  course,  requisite  to  be  a 
physiologist:  the  most  important  results  are  derived 
from  vivisections,  but  it  must  be  learned  (no  small  task) 
both  how  to  make  and  to  interpret  them. 

There  must  also  be  a  knowledge  of  surgical  pathol- 
ogy in  order  to  discriminate  between  cerebral  commotions 
resulting  from  surgical  processes  (trephining,  etc.),  and 
those  depending  upon  other  (physiological)  causes. 

Joined  with  this,  proficiency  in  MEDICAL  PATHOLOGY  is 
imperative,  in  order  to  recognize  those  pathological  con- 
ditions    (cerebral    atrophy,    general    paralysis,    cortical 


Vlll  AUTHOR  S    PREFACE. 

paralysis,  aphasia,  etc.)  which  are  so  inseparable  from  this 
study. 

There  must  be,  too,  a  degree  of  acquaintance  with  the 
science  of  PHYSICS,  as  exemplified  in  understanding  electric 
excitations,  their  number,  frequency,  diffusion,  polariza- 
tion, etc. 

As  for  anatomy,  a  thorough  knowledge  of  that  which 
concerns  the  human  subject  is  but  the  introduction  ;  com- 
parative anatomy,  histology,  embryology,  and  physiology 
are  of  still  vaster  importance,  and  for  this  purpose  we  are 
forced  to  the  study  of  another  science,  zoology.  Having 
surveyed  the  wide  field  of  zoology  and  returned  to  the 
culminating  object  of  our  study — man — necessary  com- 
parisons between  human  beings  and  races  are  impossible 
without  the  aid  of  another  science,  that  of  anthropology. 

Again,  in  cerebral  physiology  the  science  of  psychology 
is  especially  requisite,  for  no  one  who  has  not  deeply  re- 
flected upon  the  processes  of  intellection  is  capable  of 
producing  a  good  cerebral  physiology  ;  the  very  essence  of 
the  subject  would  be  to  him  a  closed  volume.  To  be  sure, 
this  science,  notwithstanding  the  many  admirable  works 
written,  and  the  labors  which  many  profound  thinkers 
have  bestowed  upon  it,  is  as  yet  in  its  rough  outline.  The 
laws  of  human  thought,  what  is  more  mysterious  !  They 
lie  at  the  very  foundation  of  our  subject.  The  movement 
of  the  heart  is  its  physiological  function  ;  thought  is  the 
physiological  function  of  the  brain.  Now  the  movement 
of  the  heart,  though  relatively  easy  to  see  and  study,  has 
required  centuries  of  gropings  and  errors  to  become  under- 
stood, and  is  there  not  much  greater  reason  to  anticipate 
like  obstacles  to  a  complete  understanding  of  the  action  of 
thought,  a  subject  so  difficult  to  examine  and  analyze  ? 


AUTHOR  S   PREFACE.  IX 

The  list  might  be  indefinitely  multiplied,  and  in  all  these 
sciences,  each  one  of  which  is  a  life-long  study,  who  can 
hope  to  be  so  perfected  as  not  to  be  justly  exposed  to 
criticism  ? 

I  have  been  and  perhaps  will  again  be  charged  by  my 
readers  with  a  lack  of  positiveness,  in  other  words  of  being 
skeptical.  But  the  very  accusation  seems  to  me  eulogis- 
tic, for  in  science  there  is  nothing  more  baneful  than  to 
treat  hypotheses  as  certainties.  On  the  contrary,  when 
serious  criticism  has  revealed  the  defects  and  feebleness 
of  an  experiment,  a  real  service  has  been  rendered,  for  it 
may  incite  to  new  experiments  and  unequivocal  conclu- 
sions. 

Inductions  from  probabilities  or  ill-demonstrated  experi- 
ments are  unreliable,  and  intelligent  skepticism  is  more 
valuable  to  the  advance  of  science  than  unbridled  enthu- 
siasm. 

In  connection  with  our  subject,  I  would  refer  to  one 
danger  which  should  be  guarded  against  and  which  has 
been  somewhat  overlooked.  That  is,  recent  labors  have 
been  accepted  too  much  to  the  exclusion  or  neglect  of 
those  further  in  the  past. 

It  is  an  unfortunate  tendency  and  one  that  results  in 
injustice.  For  example  :  in  the  physiological  history  of 
the  convolutions,  some  of  the  finest  discoveries  were  made 
by  Flourens.  There  are  few  experiments  as  interesting  as 
that  in  which  the  pigeon,  deprived  of  its  cerebral  lobes, 
sits  plunged  into  a  profound  sleep  of  everlasting  tinconscious- 
ness. 

I  most  fuily  recognize  that  recent  investigators,  Fritsche 
and  Hitzig,  Ferrier,  Charcot,  and  others  have  made  mag- 
nificent discoveries;  still  it  is  Flourens  who  stands  in  the 


AUTHOR  S   PREFACE. 


front  rank,  and  it  need  not  be  considered  that  the  science 
of  cerebral  physiology  dates  from  1872. 


I  am  gratified  that  Dr.  Fowler,  who  has  already  so  ably 
translated  Charcot's  work  upon  Localization  in  Dis- 
eases of  the  Brain,  has  deemed  my  book  worthy  the 
same  consideration.  He  has  my  full  appreciation  of  the 
compliment  and  of  the  conscientious  and  scholarly  manner 
in  which  his  labor  has  been  performed. 

Lastly,  I  do  not  feel  that,  in  addressing  itself  to  the 
American  profession,  my  volume  is  going  among  strangers, 
for  in  science  there  is  but  one  land  and  one  people. 

Ch.  Richet. 

Paris,  April  29,  1879. 


TRANSLATOR'S     PREFACE. 


Every  student  in  medicine  knows  that  an  intelligent 
recognition  of  pathology,  and  a  judicious,  rational  manage- 
ment of  disease,  are  in  exact  ratio  to  a  precise  knowledge 
of  normal  anatomy  and  physiology. 

For  this  reason,  Richet's  Physiology  and  Histology 
of  the  Cerebral  Convolutions  seems  a  natural  com- 
plement to  Charcot's  "  Localization  in  Diseases  of  the 
Brain." 

In  the  anatomical  portion,  Richet  includes  the  latest 
researches. 

As  regards  physiology,  he  indicates  those  points  which 
are  settled  beyond  dispute  ;  but  where  the  matter  is  still 
under  discussion,  the  arguments  upon  both  sides  are  faith- 
fully given,  and  the  author  conscientiously  abstains  from 
lending  bias  by  way  of  mere  personal  opinion  or  theory  ; 
he  is  preeminently  a  dealer  in  facts. 

The  author  suggested  that  an  abridged  form  of  a  little 
monograph  which  he  has  written  upon  "  POISONS  OF  THE 
Intellect  "  would  add  somewhat  to  the  interest  of  the 
physiological  part  of  the  book,  and  in  compliance  there- 
with, I  have  made  the  addition,  which  my  friend  Dr.  John 
C.  Minor  has  very  kindly  and  ably  translated  and  arranged. 
It  was  originally  written  as  a  popular  article  for  non-pro- 
fessional readers,  and  hence  the  author  has  presented  the 


Xll  AUTHOR  S   PREFACE. 

subject  as  a  study  in  psychology  rather  than  in  the  more 
exact  sciences  of  anatomy  and  physiology. 

In  order  to  bring  the  subject  within  the  required  limits, 
it  has  been  necessary  to  condense  as  much  as  the  preser- 
vation of  the  original  plan  of  arrangement  would  permit, 
and  at  the  same  time  to  eliminate  everything  that  was  not 
essential  to  the  subject.  Hence,  perhaps  the  most  inter- 
esting portion  of  the  work,  that  which  dealt  particularly 
with  illustrative  cases  and  extended  descriptions,  was 
unwillingly  sacrificed  in  order  to  present  the  work  in  its 
abridged  form. 

New  York,  June,  1879. 


INDEX   OF   ILLUSTRATIONS 


PAGE 


Fig.    i. — Pyramidal  cell  of  middle  occipital  lobe  (solitary  cell 

of  Meynert).    (Mierzejewski) 9 

Fig.  2. — Giant-cell  : — paracentral  lobe.     (Mierjewski) 9 

Fig.  3. — Section   of  cortical  cell    of  deep    layer  (mag.    800 

diam.).    (Luys) 11 

Fig.  4. — Section  of  third  convolution.  (Meynert) 16 

Cornu  Ammonis.     (Richet.) 

Plate  1 26 

Plate  II 27 

Fig.  5. — Portion  of  injected  sheep's  brain.    (Gerlach) 39 

Fig.   6. — Arteries  of  the  convolutions.     (Duret) 40 

Fig.  7. — Lateral  convolutions  and  sulci  of  human  brain. ...  48 
Fig.  8. — Inter-hemispheric    convolutions    of   human    brain. 

(Ecker) 49 

Fig.  9. — Left  hemisphere  of  dog's  brain.     (Ferrier) 50 

Fig.   10. — Tracings  of  electric  experiments.    (Richet) 66 

Fig.   11. — Tracings  of  electric  experiments.     (Richet) 66 

Fig.   12. — Tracings  of  electric    experiments.     (Franck   and 

Pitres) 67 

Fig.   13. — Dog's  brain   explanatory  of  Fritsch    and  Hitzig's 

experiments.      (Fritsch  and  Hitzig) 84 

Fig.    14. — Dog's  brain,  left  hemisphere.     (Ferrier) 84 

Fig.   15. — Monkey's  brain,  left  hemisphere.     (Ferrier)    86 

Fig.   16. — Human  brain,  left  hemisphere 87 

Fig.   17. — Tracing     of   electric    experiment.       (Franck    and 

Pitres.) 97 

Fig.   18. — Tracing    of    electric    experiment.       (Franck    and 

Pitres) 97 

Fig.   19. — Monkey's  brain,  left  hemisphere  :  lesion  producing 

blindness.     (Ferrier) 124 

Fig.  20.  — Brain  of  a  Charruas,  right  hemisphere.     (Leuret).  132 

Fig.  2i. — Brain  of  Fieschi,  right  hemisphere.     (Leuret) ....  133 
Fig.  22.  )  — Large   plate  at  end  of  work,  folded.     Tracings 
Fig.   23-  ^           of  electric  experiments.     (Richet.) 


TABLE  OF  CONTENTS. 


First  Part:  Structure  of  the  Convolutions. 

Sec.  i.  Historical,             .....  i 

2.  General  arrangement,              ...  4 

"     3.  Organized  elements,         ....  6 

"     4.  General  structure,      ....  13 

"     5.  Special  structure,              ....  19 

"     6.  Structure  in  mammifera,        .             .             .  32 

"     7.  White  substance,               ....  34 

"     8.  Vessels,           .....  38 

"     9.  Development,        .....  43 

Second  Part  :  Physiology  of  the  Convolutions. 

Anatomical  introduction,        ....  47 

Historical  introduction,                  .             .             .             .  51 

Chapter  First  :  Physiological  Properties. 

Sec.  1.  Excitability,  .....  59 

"     2.  Thermic,  electric,  and  chemical  conditions,        .  72 

"     3.  Circulation,    .....  74 

Chapter  Second  :  Functions. 

Sec.  1.  Motor  Functions,              ....  81 

A.  Methods  of  investigation,       .             .             .  81 

B.  Action  upon  the  muscles  of  animal  life,                .  83 

C.  Action  upon  the  muscles  of  organic  life,       .  99 

D.  Aphasia,                 .....  107 

E.  Theories  of  motor  innervation,          .             .  109 
Sec.  2.  Sensorial  Functions,         ....  122 

"     3.  Intellectual  Functions,           .             .             .  130 

Bibliography,         ......  141 


CEREBRAL  CONVOLUTIONS. 


FIRST  PART. 
STRUCTURE  OF   THE  CONVOLUTIONS. 

I.    HISTORY. 

Although  the  arrangement  and  the  morphology  of  the 
cerebral  convolutions  are  now  tolerably  well  known,  their 
structure  has  not  been  described  with  corresponding  exact- 
itude, and  our  latest  knowledge  upon  the  subject  is  still 
defective.  We  will  first  examine  the  opinions  of  the  an- 
cient anatomists. 

Hippocrates'  compares  the  brain  to  a  gland  :  caput  quoque 
ipsum  glandulas  habet;  nam  cerebrum  glandulce  simile. 

According  to  Malpighi2  and  Vieussens3  also,  the  cere- 
bral cortex  was  a  gland. 

With  some  reservations,  Malpighi  compares  the  cerebral 
glands  to  the  hepatic  lobule, — Non  improbabile  interim  pit- 
tans  iisdem  ctiam  acinis  (of  the  liven  has  cerebri  glandulas 
eouglobari  posse.* 

Indeed,  Malpighi  supposed  the  brain  to  be  composed  of 
fibres  and  glands — Corticales  glandulce  tortuose  pocatce  exte- 
riores  cerebri  gyros  componunt,  et  exorient  ibus  inde  medullaribus 
fibris,  sen  vaseulis,  appenduntur,  ita  ut  ubicunque  per  trans- 
fer sum  secantur  gyri,  détermina  ta  et  fir  ma  semper  glandu la- 
rum  congerie  medullœ  affuudatur. 

'Cited  by  Longet,  Anat.  et.  physiol.  du  système  nerveux,  I.,  p.  160. 
'-'  De  cerebri  cortice  dissertatio,  in   Bibl.  anat.  de  Manget,  t.  ii.,  p.  S2.   Ge- 
nève, 1699. 

3  Institut,  de  méd.,t.  iii.,  p.  109,  2d  edition. 

4  Loc.  cit.,  p.  323. 


2  CEREBRAL  CONVOLUTIONS. 

I  do  not  know  that  one  can  be  as  positive  as  Luys,1  and 
affirm  that  Malpighi  discovered  the  brain-cells  ;  yet  it 
seems  to  me  very  probable.  In  another  place  he  says  : 
glandular  inn  exiguitas  acicm  microscopii  subtcrfugit  ;  probably 
signifying  that  he  expected  to  see  the  lobules,  but  has  only 
seen  simple,  very  small,  non-agglomerated  cells  (?). 

However  it  may  be,  the  ideas  of  Malpighi  were  soon 
forgotten.  In  1698,  Ruysch,8  from  the  results  of  his  mar- 
vellous arterial  injections,  considered  the  cerebral  cortex 
as  a  vascular  network.  That  opinion,  advanced  some  time 
before  by  Leuwenhoeck,  was  generally  adopted  by  anato- 
mists. Boerhave,"  who  at  first  had  admitted  the  opinion 
of  Malpighi,  finally  adopted  that  of  Ruysch. 

The  theory  of  Ruysch  rested  upon  an  exact  fact  :  the 
extreme  vascularity  of  the  cerebral  cortex.  At  first  no 
objection  was  offered.  At  the  time  of  Haller4  (1766)  the 
opinion  was  classic.  It  was  admitted  that  there  were  ar- 
teries which  could  be  injected,  and  others  which  were  in- 
visible and  which  could  not  be  injected — all  being  plunged 
into  a  very  fine  cellular  woof.  There  were  distinguished 
in  the  brain  a  white  portion  (medulla)  and  a  gray  portion 
(cinereus  cortex)  made  up  by  a  mesh  of  arteries. 

The  first  anatomist  who  gave  a  good  idea  of  the  cere- 
bral structure  was  probably  Vicq  d'Azyr."      He  pointed 

1  Le  cerveau  et  ses  fonctions,  p.  15. 

■'  Thesaurus  anatom.,  vi.,  n.  73,  thés,  iv.,  n.  78,  p.  78  ;  p.  Si  (citation  of  Hal- 
ler, t.  iv.,  epist.  xi.,  p.  24). 

3  Cited  by  Haller,  elementa  phys.,  iv.,  p.  25.  4  Loc.  cit.,  p.  27. 

5  Vicq  d'Azyr  thus  expresses  himself  :  "In  preparing  the  centrum  ovale  of 
Vieussens,  if  the  form  of  the  posterior  cerebral  convolutions  which  lie  upon 
the  tentorium  cerebelli  be  examined,  there  generally  will  be  noticed  several 
that  are  remarkable  on  account  of  a  while  line  which  longitudinally  divides 
the  cortex,  following  all  its  conlours,  and  which  give  to  that  portion  of  the  cor- 
tex the  appearance  of  a  striped  ribbon.  I  have  found  that  arrangement  in  no 
other  region  of  the  brain."  That  remarkable  observation  of  Vicq  d'Azyr, 
though  not  overlooked,  was  not  utilized,  and  it  is  but  recently  that  Broca  was 
the  first  to  make  apparent  its  importance. —  Upon  the  special  structure  of  the 
inferior  convolutions  of  the  occipital  lobe  ;  constant  presence  of  the  striped  rib- 
bon of  Vicq  d'Azyr. — Bull,  de  la  soc.  d'anthropologie,  1861,  /.  ii.,p-  313. 


STRUCTURE  OF  THE  CONVOLUTIONS.  3 

out  that  the  gray  cortex  was  really  composed  of  three 
layers  :  a  white  layer  between  two  gray  layers,  giving  to 
the  gray  substance  the  appearance  of  a  striped  ribbon. 

The  fact  was  generally  accepted,  being  exact  and  indis- 
putable. Gennari,1  however,  admits  the  existence  of  a 
peculiar  yellow  substance  between  the  central  white  sub- 
stance and  the  cortex.  Subsequent  observations  have 
shown  that  this  yellow  layer  is  in  reality  the  deeper  por- 
tion of  the  cortex. 

In  1 840  appeared  the  standard  work  of  Baillarger  a  ;  that 
eminent  anatomist  announced  that  the  gray  portion  of  each 
convolution  was  composed  of  six  layers,  alternately  gray 
and  white. 

To  demonstrate  his  proposition,  Baillarger  examined 
the  convolutions  both  by  transmitted  and  direct  light. 
When  rendered  transparent,  the  gray  layers  appeared 
clear,  the  white  opaque.  Baillarger  showed  that  in  voung 
infants  this  appearance  was  very  marked,  and  could  be 
found  even  in  the  foetus  of  four  or  five  months. 

It  was  about  this  time  that  the  microscope  was  brought 
into  use,  and  with  that  the  minute  structure  of  the  convo- 
lutions could  be  investigated.  The  discovery  of  nerve- 
cells  by  Ehrenberg,  Valentin,  Purkinje  (1835  to  1840)  de- 
monstrated the  presence  of  nerve-cells  very  variable  in 
form  in  the  cerebral  cortex. 

Whatever  may  be  the  interest  belonging  to  the  revolu- 
tions from  that  time-to  the  present  concerning  the  subject 
of  nerve-tissue,  I  cannot  stop  to  consider  it. 

Respecting  the  convolutions,  Mevnert  is  certainly  the 
first  who  has  given  an  exact  description  accompanied  with 
good  illustrations. 

At  the  same  period,  Luys,  in  his  grand  work  upon  the 
nervous  system,  established  the  connection  of  the  cortical 
and  ganglionic  systems  of  the  brain.    After  Luys  and  Mey- 

1  Cited  by  Longet,  loc.  cit.,  t.  i.,  p.  608. 

2  Recherches  sur  la  structure  de  la  couche  corticale  des  convolutions  du  cer 
veau. — Mém.  de  l'Acad.  de  méd.,  t.  viii.,  1840. 


4  CEREBRAL   CONVOLUTIONS. 

nert  ought  to  be  cited  the  work  of  Betz,  who  first  described 
certain  cells  in  the  motor-centres  of  the  cortex.  Also  the 
staff  of  the  Lunatic  Assylum  of  London  has  recently  pub- 
lished a  series  of  valuable  works  upon  the  structure  of  the 
convolutions. 

Reviewing  this  rapid  history  we  find  : 

i  st.  That  probably  Malpighi  discovered  the  cells  and 
nerve-fibres  of  the  cerebral  cortex. 

2d.  That  Vicq  d'Azyr  and  Baillarger  have  well  de- 
scribed the  structure  of  the  convolutions  as  seen  by  the 
naked  eye. 

3d.  That  Meynert,  Luys,  and  Betz  have  made  known 
the  microscopic  structure. 


Sec.  2.  GENERAL  ARRANGEMENT  OF  THE 
CONVOLUTIONS. 

If  a  human  brain,  divested  of  its  membranes,  be  examined, 
it  will  be  observed  that  the  surface  is  of  an  ash-gray,  cov- 
ered with  a  multitude  of  furrows  variable  in  dimensions, 
irregular  in  appearance,  and  which  limit  the  projections, 
the  elevations  of  which  are  the  cerebral  convolutions.1 

Thus  each  convolution  forms  an  oblong  mass,  with  blunt 
and  rounded  angles  so  confounded  at  each  end  with  other 
convolutions  that  the  precise  point  of  commencement  and 
ending  can  only  be  schematically  designated.  It  rests 
against  one  or  more  of  the  neighboring  convolutions,  and 
the  intervening  furrow,  empty  when  the  pia  mater  and 
arachnoid  are  removed,  is,  when  the  membranes  are  in 
place,  filled  with  vessels.     The  joining  faces  of  the  convolu- 

1  Gratiolet  proposed  to  replace  this  unwieldly  and  inexact  term  (as  applied 
to  the  lower  mammifera  at  least)  by  the  word  fold  (plis),  but  usage  has  not 
sanctioned  the  term.  Perhaps,  as  Broca  suggests,  they  might  be  called  volu- 
tions. 


STRUCTURE  OF  THE  CONVOLUTIONS.  5 

tions  are  filled  out,  and  they  so  join  each  other  that  the 
intermediate  furrow  is  divided  into  two  parts,  the  superior 
one  for  the  veins,  the  inferior  for  the  arteries.  The  entire 
gray  cortex,  here  rising  into  a  convolution,  there  sinking 
into  a  furrow,  may  be  looked  upon  as  a  continuation  of  a 
single  layer  folded  upon  itself.  This  was  Gall's  idea,  an 
ingenious  one,  and  well  calculated  to  express  in  schematic 
and  easily-to-be-remembered  manner  the  construction  of 
the  exterior  cerebral  covering. 

The  gray  and  white  substance  of  the  convolutions  form 
a  cortex  sometimes  called  convolutionary,  which  should, 
according  to  Burdach  and  Broca,1  be  called  palleum  or 
manteau  (mantle). 

The  remainder  of  the  cerebral  hemisphere  forms  the 
body  of  the  brain. 

The  convolutions  are  separated  by  furrows  of  various 
depths,  and  according  to  their  depths  and  their  morphol- 
ogy they  are  differently  named,  fissures,  furrows,  creases." 

It  should  be  especially  observed  that  none  of  these 
fissures  or  furrows  serve  to  completely  separate  adjoin- 
ing convolutions,  the  continuity  of  which  is  never  inter- 
rupted. To  employ  a  common  comparison,  the  cerebral 
convolutions  represent  a  chain  of  mountains  in  which  no 
valley  traverses  in  such  manner  as  to  isolate  the  mountain 
peaks  and  plateaux.  Nowhere  upon  the  brain  do  two 
transverse,  parallel  furrows  intersect  two  longitudinal 
parallel  furrows.  In-short,  all  the  furrows  are  incomplete — 
insufficient,  as  it  were — as  though  they  were  unable  to  at- 
tain to  the  extremity  of  the  convolution  with  which  they 
commenced.  Perhaps  this  may  be  of  some  importance  in 
a  functional  point  of  view. 

Broca  thus  defines  the  term  convolution  :a — "  The  word, 


1  Revue  d'anthropologie,  1878,  p.  197. 

2  See  article,  Circonvolutions  (Pozzi),  Diet,  encyclop.  des  sciences  me'd.,p. 
342. 

3Anatomie  comparée  des  circonvolutions  cérébrales. — Revue  d'anthropologie, 
1878,  p.  391. 

2 


6  CEREBRAL   CONVOLUTIONS. 

convolution,  which  has  heretofore  been  employed  to 
designate  some  portion  of  the  folded  surface  of  the  brain, 
has  now  come  to  have  an  accepted  meaning  :  it  is  applied 
to  the  subdivisions  of  lobes,  and  if  in  some  cases  a  lobe  can 
be  composed  of  a  single  convolution,  on  the  other  hand  no 
convolution  can  exceed  the  limits  of  its  lobe,  even  though 
it  may  continue  more  or  less  directly  with  a  convolution 
of  a  joining  lobe." 

As  fissures  differ  in  importance,  so  also  do  convolutions. 
To  slightly  marked  furrows  and  to  creases  belong  convo- 
lutions which  are  barely  outlined,  and  which,  according  to 
Pozzi,  may  be  called  folds.  But  however  greatly  the  fur- 
rows and  convolutions  may  vary  in  size,  the  structure  is 
always  the  same,  and  consequently  a  general  description 
applies  to  the  entire  mass. 

In  certain  parts  of  the  brain  the  cortex  folds  upon  itself, 
and  by  invagination  forms  an  inverted  convolution  (gyrus 
Hippocampi),  but  here,  too,  the  structure  and  arrangement 
are  the  same. 

A  point  which  should  be  well  observed,  but  which  we 
cannot  properly  dwell  upon  here,  is  that  the  convolutions, 
in  most  individuals  at  least,  are  not  symmetrical. 


Sec.    3.     ORGANIZED  ELEMENTS  OF  THE  CON- 
VOLUTIONS. 

As  observed  by  the  anatomists  of  the  last  century,  each 
convolution  is  composed  of  an  external  gray  layer  which 
exactly  fits  to  the  central  white  part  :  both  receive  vessels. 
We  have,  therefore,  to  study  : — 

1  st.  The  gray  layer,  the  cortex  of  the  convolution  (cor- 
tex cerebri). 

2d.  The  white  layer,  which  forms  the  axis. 

3d.  The  vessels  distributed  to  each  layer. 


STRUCTURE   OF   THE   CONVOLUTIONS.  7 

The  gray  cortex  probably  is  not  a  homogeneous  layer  ; 
Baillarger1  maintains  that  it  is  composed  of  six  layers,  being 
arranged  from  without  towards  the  centre  as  follows  : — 

i.  White  layer. 

2.  Gray  layer. 

3.  White  layer. 

4.  Gray  layer. 

5.  White  layer. 

6.  Gray  layer. 

The  four  internal  layers  are  often  confounded  in  a  single 
yellowish-red  layer,  by  some  authors  described  as  a  special 
layer.'-     Meynert  holds  to  five  layers.3 

Mathias  Duval'  admits  either  five  or  six  layers  accord- 
ing as  one  counts  the  fifth  and  sixth  as  one  or  two. 

Lewis5  admits,  in  the  human  subject,  five  layers.0 

All  these  layers  of  gray  substance  contain  four  varie- 
ties of  organized  elements  :  pyramidal,  giant  and  fusiform 
cells,  and  granules  (myelocytes). 

1  st.  Pyramidal  Cells. — -These  are  the  most  numerous 
and  are  generally  small  and  more  difficult  to  discover  than 
in  the  corresponding  layers  of  the  cerebellum.  They  are 
provided  with  several  slender,  pale,  ramified  prolongations 
of  which  three  kinds  can  be  distinguished.7 

a.  The  pointed  extremity  of  the  cell,  directed  towards 
the  periphery,  continues  by  a  fine  thread  which  bends 
backwards8  (pyramidal  prolongation  of  Meynert). 

1  Loc.  cit.  et  Comptes  rendus  de  l'Ac.  des  sciences. 

-See  Kôlliker,  Elém.  d'hfstol.,  French  trans.,  p.   357. 

3Journ.  de  l'anat.,  1874,  t.  x.,  p.  100. — Pouchet,  Traité  d'hist.,  p.  307. 

4  Art.  Nerveux  (système)  du  Diet,  de  méd.  et  de  chirurgie  pratiques,  p. 
480. 

5  On  the  Comparative  Structure  of  the  Cortex  Cerebri  ;  Brain.     1878,  p.  82. 

6  In  Henle's  Handbuch  der  Nervenlehre,  1871,  p.  277,  will  be  found  a  com- 
plete resume  of  opinions  expressed  respecting  the  number  of  layers  contained 
in  the  gray  cortex. 

1  Pouchet  and  Tourneux  :  Traité  d'histol.,  p.  307. — Meynert:  Strieker's 
Handbuch,  I.,  p.  708. 

s  This  opinion,  contrary  to  that  of  Biitzke  (Archiv.  fur  Psychiatrie,  1872,  t. 
iii.,  p.  300,  has  been  admitted  by  Arndt  (Arch,  fiir  microscop.  Anat.,   1874). 


8  CEREBRAL   CONVOLUTIONS. 

b.  Laterally  the  cell  gives  from  each  side  prolongations 
which  are  either  oblique  or  perpendicular  to  its  axis. 

c.  At  the  base  of  the  cell  is  a  prolongation  analogous 
to  the  prolongation  of  Deiters  (basal  prolongation  of  Mey- 
nert). 

These  cells  are  generally  in  form  of  pyramids  or  trian- 
gles, the  bases  of  which  face  the  white  substance,  the 
points  being  directed  towards  the  periphery. 

These  two  cellular  prolongations  have  been  very  well 
represented  in  their  normal  state  by  Mierzejewski  in  two 
figures,  which  we  here  reproduce. 

In  the  human  subject  it  is  difficult  to  see  the  basal  pro- 
longation, but  that  is  no  reason,  as  Arndt '  has  vainly  en- 
deavored, for  putting  in  question  its  existence. 

Naturally  it  is  very  difficult  to  follow  to  the  terminations 
of  the  prolongations,  and  perhaps  only  a  moderate  degree 
of  confidence  should  be  given  to  the  investigations  of 
Golgi.2  Golgi  believed  to  have  seen  the  basal  prolonga- 
tion of  the  pyramidal  cells  passing  backwards,  and,  after  a 
short  distance,  dividing  and  giving  lateral  branches,  which, 
bending  back  again,  ran  to  the  periphery  of  the  brain. 
The  other  prolongations  are  in  connection  with  the  con- 
junctive or  granular  cells.  The  anastomoses  of  the  various 
parts  were  first  illustrated  by  Luys,  then  by  Besser 3  and 
Arndt. 

According  to  Koschewnikoff,  the  basal  prolongation  may 
be  followed  into  the  white  substance,  where  it  is  surrounded 
by  myéline,  and  becomes  the  axis-cylinder  of  a  nerve.4 

Boll  '"  considers  the  pyramidal  form  of  the  cells  the  result 
of  the  preparation  :  treated  with  osmic  acid,  which  sur- 
prises them  as  it  were  living,  they  are  circular. 

1  Arndt  :  Studien  tiber  die  Architectonik  der  Grosshirnrinde,  Max  Schulze's 
Archiv,  1874. 

2  Sulla  struttura  della  sostansa  grigia  del  cervelle».  Communie,  preventiva. 
Gaz.  méd.  ital.     Lomb.,  ser.  6,  t.  vi. 

3  Eine  Anastomose  fur  die  Centralen  Ganglien-Zellen.  Virchow's  Archiv, 
Bd.  36.  5  Arch,  fur  Psych.,  1873. 

4  Koschewnikoff  :  Arch,  de  Schultze,  1869,  p.  332  et  375. 


STRUCTURE  OF  THE  CONVOLUTIONS. 


Fig.  i. 


Fig.  2. 


Fig.  i  (After  Mierzejewski). — Pyramidal  cell  of  the  middle  occipital  lobe 
(solitary  cell  of  Meynert). 

Fig.  2. — Giant  cell,  common  to  the  paracentral  lobe.  At  the  lower  part,  the 
basal  prolongation  ;  at  the  upper  part,  the  pyramidal  prolongation. 


IO  CEREBRAL   CONVOLUTIONS. 

They  are  often  supplied  with  pigmentary  granulations. 

According  to  Luys,1  they  have,  in  fresh  specimens,  an 
amber-yellow  color,  and  are  provided  with  a  brilliant 
nucleus  and  a  nucleolus. 

It  seems  possible  to  penetrate  still  further  into  the  inti- 
mate structure  of  the  cell.  Without  discussing  this  ques- 
tion, histologically  so  interesting,  we  would  remark  that 
the  researches  of  Harless,  Wagner,  Flemming,  Stark,  and 
others  indicate  that  the  nerve-cell  is  a  very  complicated 
structure.  The  study  of  the  minute  structure  of  the  nerve- 
cells,  however,  has  generally  been  pursued  in  the  spinal 
cord  of  the  ox  (anterior  cornua),  few  observations  having 
been  made  of  the  cells  in  the  reticulum  of  the  cerebral  cor- 
tex. 

Luys,  however,  has  well  described  these  cells,  and  below 
is  the  plate  which  he  gives  (Fig.  3). 

That  learned  anatomist  considers  the  cellular  body  to 
possess  a  truly  reticulated  structure.  The  reticulum  is 
made  up  of  fibrillar,  which,  arranged  like  the  trellis  of  a 
willow-basket,  converge  towards  the  nucleus  of  the  cell. 

Some  of  the  pyramidal  cells  are  small,  10  mm.;  others 
average  22  mm.  According  to  Luys,  who  first  described 
them,  their  number  approximates  about  no  to  the  square 
millimetre — a  considerable  number,  considering  the  sur- 
face of  the  brain,  as  compared  to  the  small  number  of  the 
medullary  cells.  Thus  there  are  very  many  more  cells  in 
the  brain  than  in  the  spinal  cord. 

It  appears  that  the  protoplasmic  prolongations  of  all  the 
cells  anastomose  in  such  way  as  to  form  a  fine  nerve-net- 
work, analogous  to  that  found  in  the  spinal  cord  (Gerlach 
and  Boll.) 

Biitzke2  considers  a  distinctive  characteristic  of  the  nerve- 
cells  of  the  cortex  cerebri  to  be  the  longitudinal  striation 
of  the  cellular  body,  as  well  as  of  its  prolongations  ;  the 
same  as  transverse  striations  characterize  muscular  fibre. 

1  Le  cervau,  1876,  p.  14.  ■  Loc.  cit.  p.  589. 


STRUCTURE  OF  THE  CONVOLUTIONS. 


II 


2d.  Giant-cells. — There  is  another  variety  of  cells  found 
in  certain  regions,  which  are  remarkable  on  account  of  their 
size.  They  are  faithfully  described  by  Betz,1  who  calls 
them  giant-cells.2  They  attain  a  diameter  of  50  mm.  Mier- 
zejewski  says  that  they  always  contain  a  yellowish-brown 
pigment.3     It  is   generally   believed  that   they   are   very 


\ 


Fig.  3. 

Fig.  3  (after  Luys). — A  cortical  cell  of  the  deep  layers — about  800  diameters. 
The  cell  is  divided  in  its  long  axix,  and  the  interior  texture  can  be  seen. 

A  represents  the  superior  prolongation,  coming  from  the  body  of  the  cell. 
B,  lateral  and  posterior  prolongations.  C,  spongy,  areolar  substance,  in  which 
is  found  the  cellular  stroma.  D,  the  cell  seems  to  have  the  same  thickness  as 
the  stroma  ;  it  sometimes  has  a  radiated  appearance.  E,  the  brilliant  nucleolus 
is  also  decomposable  into  secondary  fibres. 

1  Anat.  Nachw.  zweier  Gehirn-Centra.     Centralblatt,  1S74,  Nos.  37  and  38. 

-  Mierzejewski  (Arch,  de  physiol.,  1875,  p.  226)  observed  them  one  year  prior 
to  Betz  perhaps,  but  the  determining  of  their  topography  undoubtedly 
belongs  to  Betz.  3  Loc.  cit.,  p.  228. 


12  CEREBRAL   CONVOLUTIONS. 

analogous  to  the  pyramidal  cells,  from  which  they  differ 
only  in  size. 

3d.  Myelocytes. — The  myelocytes,  or  granules,  are 
especially  abundant  in  the  lower  layers  of  the  cortex.  They 
should  not  be  regarded  as  cells,  but  as  cellular  nuclei,  the 
cellular  body  which  surrounds  them  being  very  reduced, 
and  requiring  special  preparation  in  order  to  be  seen. 
There  is  a  lack  of  accord  concerning  the  nature  of  these 
elements,  though  present  opinion  seems  inclined  to  view 
them  as  embryonic  nerve-cells. 

Biitzke  holds  that  between  the  granules  and  the  true 
conjunctive  cells  there  is  an  entire  series  of  intermediate 
bodies.  Perhaps  observation  has  here  been  too  much 
adapted  to  the  support  of  a  theory. 

It  is  possible  that  there  may  be  in  the  gray  cortex  cere- 
bri every  transition  between  these  cells  (of  which  the 
nuclei  are  the  granules)  and  the  nerve-cells  proper.  Per- 
haps we  should  consider  as  the  element  of  transition  from 
the  granule  to  the  nerve-cell,  these  irregular,  globular,  non- 
pyramidal  cells  described  by  Meynert,  and  apparently 
resembling  the  elements  of  the  granular  layer  of  the  retina. 

All  this  is  still  obscure. 

4th.  Fusiform  Cells. — This  variety  has  been  described 
bv  Mernert,  and  prior  to  him  by  Berlin  ;'  they  are  fusiform 
(spindelfôrmig),  generally  bipolar,  one  prolongation  being 
directed  towards  the  periphery,  the  other  towards  the 
centre.  According  to  Lewis,  they  are  found  in  every  part 
of  the  encephalon,  and  always  in  the  most  internal  layer  of 
the  cortex,  which  they  serve  to  characterize.  They  are 
very  abundant  in  the  claustrum  (avant-mur),  as  we  will  see 
further  on. 

Between  the  fusiform,  pyramidal,  and  giant-cells  there 
exists  a  fine,  granular,  amorphous  substance  more  or  less 
abundant,  a  description  of  which  has  been  given  by  Robin. 

1  Berlin  :  Beitrage  zur  Structurlehre  der  Gross-Gehirnwindungen.  Erlan- 
gen,  1858.  J, 


STRUCTURE  OF  THE  CONVOLUTIONS.         1 3 

German  authors  generally  consider  this  amorphous  mat- 
ter to  be  conjunctive  tissue  ;  concerning  the  myelocytes, 
anatomists  are  greatly  at  variance  ;  but  that  discussion 
would  carry  us  too  far  and  outside  of  our  subject. 

To  complete  a  mention  of  all  the  elements  to  be  found 
in  the  gray  cortex,  we  should  add  the  very  minute  fibril 
prolongations  of  the  nerve-cells,  and  also  the  vessels  sur- 
rounded by  a  lymphatic  sheath. 

A  résumé  gives  as  follows  : 

i.  Pyramidal  cells. 

2.  Giant-cells. 

3.  Myelocytes. 

4.  Fusiform  cells. 

5.  Amorphous  substance. 

6.  Fibrillary  nerve-prolongations. 

7.  The  vessels  with  their  lymphatic  sheaths. 


Sec.  4.  STRUCTURE   OF    THE   CONVOLUTIONS 
IN   GENERAL. 

Let  us  now  examine  the  relations  of  these  diverse  ele- 
ments and  the  arrangement  of  the  concentric  layers.  We 
will  cite  especially  from  the  works  of  Meynert1  and  Lewis." 

We  will  describe,  as  Meynert  has  done,  the  general  type 
of  the  convolutions,  following  this  with  the  special  struc- 
tures of  this  or  that  one. 

A.  First  Layer  (external). — This  layer  is  formed  almost 
exclusively   of  amorphous   substance  and  contains  few  if 

1  Der  Bau  der  Grosshirnrinde  und  seine  ôrtlichen  Verschiedenheiten,  Wien. 
Med.  Jahrb.,  1869;  Jour,  de  l'anat.,  t.  viii.,  1S72,  p.  106;  t.  x.,  1874,  p.  98. 
Strieker's  Handbuch  fiir  Geweblehre,  t.  i„  p.  694  et  suiv.  An  excellent  îësumé 
of  the  latest  microscopic  researches  is  to  be  found  in  Charcot's  Leçons  sur  les 
localisations,  1876,  p,  20  et  suiv. 

*  On  the  Comparative  Structure  of  the  Cortex  Cerebri.  Brain,  1878,  No.  1, 
p.  79. 


14  CEREBRAL   CONVOLUTIONS. 

any  nerve-cells.  To  the  unaided  eye  it  appears  white,  as 
Baillarger  long  since  observed.  Kolliker  described  and 
figured  it1  as  being  especially  composed  of  very  fine,  inter- 
mingling tubes.  They  are  the  fibres  which  Valentin,  at 
the  commencement  of  microscopy,  called  terminal  handles, 
indeed,  according  to  Kolliker,  such  would  be  their  appear- 
ance. This  layer  contains  few  vessels  ;  only  the  arterioles 
going  from  the  pia  mater  to  the  cortex.  This  has  been 
observed  by  Duret;2  besides,  it  is  a  general  law  in  the 
structure  of  the  nervous  system  that  the  parts  richest  in 
cells  are  the  ones  most  abundantly  supplied  with  blood- 
vessels.    The  illustration  by  Luys3  is  very  exact. 

Meynert  and  Kolliker  regard  this  layer  as  conjunctive  ; 
that  opinion,  however,  is  not  general,  and  Henle,  Wagner, 
Stilling,  and  Robin  think  it  a  true  nerve-layer. 

According  to  Meynert,  its  thickness  in  different  animals 
would  correspond  to  the  cortex  entire  ;  one-eighth  for  man, 
one-seventh  for  the  monkey,  one-sixth  for  the  dog,  one- 
fifth  for  the  cat,  one-fourth  for  the  mole,  one-third  for 
the  calf.  According  to  Lewis,4  in  the  sheep  its  thickness 
would  be  about  0.55  mm.,  the  entire  thickness  of  the 
cortex  being  about  three  mill.,  that  is  about  one-fifth. 

Lewis  gives  to  the  external  layer  in  the  human  brain  a 
diameter  of  from  .250  to  .340  millimetres,  about  the 
fifteenth  or  sixteenth  part  of  the  entire  thickness  of  the 
cortex,  a  figure  notably  different  from  Meynert's. 

According  to  the  same  author,  there  are  immediately 
under  the  pia  mater,  cells  analogous  to  the  cells  of  Deiters, 
adherent  to  the  vessels  and  so  connected  with  them  and 
the  pia  mater  that  in  removing  the  vascular  membrane  of 
the  encephalon  the  first  layer  of  the  cortex  is  taken  with  it. 

1  Elém.  d'histol.,  French  transi.,  1872,  p.  399,  fig.  206. 

2  Arch,  de  physiol.,  t.  vi.,  pi.  6,  figs.  2  et  3. 

3  Le  cerveau,  p.  12,  fig.  1  ;  the  cut  is  a  faithful  reproduction  of  the  beautiful 
photographs  which  M.  Luys  has  kindly  shown  me. 

4  Loc.  cit.,  p.  92.  See  the  excellent  plates  which  he  has  given  of  the  struc- 
ture of  the  human  convolutions  (plate  1),  of  the  cat's  (plate  2),  of  the  sheep's 
(plate  3). 


STRUCTURE  OF  THE  CONVOLUTIONS.         1 5 

He  has  seen  this  both  in  man  and  in  the  sheep  ;  Major  has 
noticed  the  like  with  the  baboon.1 

Boll  and  some  other  authors  (Gerlach,  Golgi)  hold  the 
outer  layer  to  be  mostly  composed  of  Deiters'  cells. 

B.  Second  Layer  (compact  pyramidal). — The  second 
layer  is  almost  entirely  composed  of  numerous  small  pyra- 
midal cells  crowded  against  each  other.  Lewis  gives  to 
these  cells  a  diameter  of  from  9  to  13  mm.  They  are  a  little 
larger  than  the  cells  of  the  first  layer.  There  is  a  little 
amorphous  matter.2 

This  layer  is  generally  thin.  The  schematic  tables  of 
Lewis  make  it  the  thinnest  of  all  the  cortical  layers.  Its 
thickness  seems  to  be  tolerably  constant,  not  only  in  the 
various  regions  of  the  encephalon,  but  also  with  various 
animals.  Luys  considers  it  the  zone  of  the  sensorium 
commune;  the  opinion,  however,  is  yet  a  hypothesis. 

C.  Third  Layer  [ammonique). — The  third  layer  is  also 
composed  of  pyramidal  cells,  but  of  a  larger  size  than  the 
preceding,  some  of  them  reaching  a  diameter  of  51  mm. 
(Lewis).  By  some,  the  layer  is  divided  into  two  distinct 
layers  and  indeed  the  most'  voluminous  cells  seem  to  pre- 
dominate in  the  inner  portion  of  the  layer.  Meynert 
thinks  the  cells  fusiform  rather  than  pyramidal,  and  pro- 
poses to  name  the  layer,  the  Layer  of  the  cornu  Ammonis, 
as  the  fusiform  cells  are  the  only  kind  found  in  the  cornua 
Ammonis.  In  addition  to  these  cells,  there  are  in  this 
layer  fasciculi  of  medullary  fibres  which  rise  perpendicu- 
larly to  the  surface-  of  the  cortex,  forming  columns-like 
between  the  groups  of  pyramidal  cells  ;  the  arrangement 
is  well  depicted  in  the  illustrations  of  Luys  and  Meynert. 

It  should  be  observed  that  this  third  layer  is  thicker 
than  the  first  two  layers  combined.  Its  appearance  differs 
greatly  according  to  the  region  of  the  brain  examined  and 

1  Observations  on  the  brain  of  the  Chacma  Baboon.  Journal  of  Mental 
Science,  Jan.,  1876,  p.  49S  (see  plate  1). 

-  This  layer  has  been  well  represented  by  Duval  :  art.  Nerfs,  du  Diet,  de  Méd. 
et  chir.  prat.,  p.  480,  fig.  74. 


i6 


CEREBRAL   CONVOLUTIONS. 


►3      / 


4,  M;U 


itell 


this  is  chiefly  dependent 
upon  the  presence  or  not 
of  the  giant-cells  of  Betz 
which  are  only  found  in 
the  motor  centres  of  the 
cortex  cerebri.1 

D.  Fourth  Layer  (gran- 
ular).— The  Fourth  Layer 
is  chiefly  composed  of 
myelocytes,  lying  regularly 
side  by  side  :  the  general 
arrangement  of  this  layer 
allows  it  to  be  compared 
with  the  granular  layer  of 
the  retina,  an  interesting 
similarity  to  which  we  will 
have  occasion  to  revert. 

E.  Fifth  and  Sixth 
Layers  (claustral). — This 
layer  seems  to  be  the  most 
important  of  all  those 
which  combine  to  form 
the  cortex  cerebri.  It  has 
a  reddish-yellow  color 
(Kôlliker)  due  to  pigment- 
ary cells  (which  are  very 
abundant  in  aged  subjects), 
and  is  made  up  of  cells,  and 

FlG.  4  (after  Meynert). — Section  of 
the  third  frontal  convolution  of 
man.     (Enlarged  500  times.) 

1.  Superficial  layer,  poor  in  nerve 
elements. 

2.  Layer  of  small  pyramidal  cells. 

3.  Layer  of  great  pyramidal  cells. 

4.  Layer  of  globular  cells. 

5.  Layer  of  fusiform  cells. 


See  Charcot,  loc.  cit.,  p.   27. 


STRUCTURE  OF  THE  CONVOLUTIONS.         \J 

of  fasciculi  which  form  isolated  loops,  the  convexities  of 
which  are  turned  towards  the  surface  of  the  brain.  The 
fibres  composing  the  fasciculi  are  at  first  about  2.6  to  6.7 
mm.  in  size,  but  at  the  external  portion  they  become  ex- 
tremely fine,  0.9  to  1.8  mm.  in  size  (Kôlliker). 

Some  authors  have  thought  that  they  have  seen  these 
fasciculi  ramify  and  divide,  within  the  cerebral  cortex,  be- 
tween the  gray  and  white  substance,1  but  that  appears  yet 
doubtful. 

It  is  important  to  study  also  the  cells.  Their  form  is  so 
characteristic  that  Lewis  terms  this  inner  layer  of  the 
cortex  the  ganglionic  layer.  They  are  sometimes  stel- 
late, sometimes  pyramidal,  and  sometimes  fusiform  (large 
cells  of  volition  of  Robin).  The  fusiform  cells  are  espe- 
cially abundant  at  the  deeper  part  of  the  fifth  layer,  so 
much  so  that  it  may  be  viewed  as  a  sixth  layer  (Meynert). 
These  cells  generally  present  a  cylinder-axis  (prolongation 
of  Deiters  ;  basal  prolongation  of  Meynert)  directed  to- 
wards the  white  cerebral  substance.  Meynert  thinks  they 
ought  not  to  be  called  bipolar,  that  they  probably  give 
off  other  lateral  prolongations  more  difficult  to  see. 

The  dimensions  of  the  fusiform  or  pyramidal  cells  are 
sometimes  comparatively  enormous,  as  has  been  observed 
by  Betz.  Lewis  gives  to  the  largest,  diameters  of  126  mm. 
The  dimensions,  however,  vary  greatly,  as  we  will  see  fur- 
ther on,  according  to  the  regions  examined.  The  fifth  layer 
has  nearly  the  thickness  of  the  third.  In  a  rough  way,  allow- 
ing the  entire  cortex  a  thickness  of  three  millimetres,  the 
internal  or  fifth  layer  would  have  one  millimetre,  the  third 
the  same,  and  the  first,  second,  and  fourth  combined,  one 
millimetre  ;  of  course  this  is  but  approximative,  still  it  is 
sufficiently  close  to  the  observations  which  I  have  made 
upon  various  preparations,  and  to  the  illustrations  of  the 
various  authors. 

As  to  a  name  for  this  last  layer  :  As  Meynert  compares 


1  Hessling  and  Schaffner,  cUed  by  Kôlliker,  lue.  cit.,  p.  402. 


I  8  CEREBRAL   CONVOLUTIONS. 

it  to  the  claustrum  {avant-mur),  and  as  Vicq  d'Azyr,  who 
first  closely  studied  the  avant-mur,  called  that  the  claus- 
trum, 1  would  propose  to  call  the  last  cortical  layer  the 
claustral  layer,  a  term  which  has  the  advantage  of  recall- 
ing- the  discovery  of  Vicq  d'Azyr,  and  which  at  the  same 
time  does  not  prejudge  its  function. 

Thus  we  would  have  the  following  layers  : 

i.  External  limiting  layer. 

2.  Compact,  pyramidal  layer. 

3.  Layer  ammonis. 

4.  Granular  layer. 

5.  Claustral  layers,  superficial  and  profound.1 

The  entire  gray  layers  of  the  brain  have  a  certain  thick- 
ness, which  the  medical  superintendents  of  the  insane  have 
frequently  studied  in  order  to  ascertain  if  there  exists  a 
relation  between  its  dimension  and  the  mental  condition 
of  their  patients.  Their  results  are  not  yet  definite.  It  is 
supposed,  however,  that  the  greatest  depth  of  the  cortex  is 
to  be  found  in  the  brains  of  the  most  intelligent. 

H.  Major,  with  the  aid  of  an  ingenious  instrument  (Te- 
phrylometre)  has  ascertained  : 

1  st.  That  the  thickness  of  the  cortex  varies  considerably 
in  the  different  convolutions  of  the  same  brain. 

2d.  That  the  variations  in  thickness  were  not  homolo- 
gous in  different  brains.  Unfortunately  these  researches 
have  been  made  upon  the  insane,  and  cannot  serve  in  any 
way  to  elucidate  that  very  interesting  question  in  normal 
anatomy.2 

The  designations  given  are  those  which  we  shall  hence- 
forth employ  ;  they  will  avoid  fatiguing  repetitions  and 
facilitate  descriptions. 

1  These  divisions  must  not  lead  to  the  supposition  that  the  layers  are  dis- 
tinctly marked.  The  limits  of  the  layers  are  to  a  considerable  degree  artificial, 
and  vary  somewhat  according  to  the  will  of  the  observer,  and  to  the  process 
employed  in  making  the  preparation  (Luys). 

3  H.  Major  :  A  new  Method  of  Determining  the  Gray  Matter  of  Convolutions. 
Lunatic  Asylum  Report,  1872,  p.  67. 


STRUCTURE  OF  THE  CONVOLUTIONS.         19 


Sec.  5.  STRUCTURE  OF  INDIVIDUAL  CONVO- 
LUTIONS. 

We  will  first  study  the  motor  and  the  sensorial  zones  of 
the  cortex,  and  then  the  special  convolutions  (the  lobe  of 
the  island  of  Reil,  gyrus  hippocampi,  olfactive  bulb,  etc). 

The  anatomical  difference  in  the  motor  and  sensorial 
zones  escaped  Meynert,  and  it  was  only  later,  guided  by 
physiology  and  pathology,  that  anatomists  have  been  able 
to  discover  it. 

An  important  point  well  brought  into  relief  by  Lewis  is. 
that  these  differences  between  the  zones  are  never  abrupt, 
it  is  always  gradual,  giving  place  to  a  transitional  zone  as 
it  were. 

We  will  first  study  the  type  of  the  paracentral  lobule, 
as  it  has  been  studied  by  Betz. 

Morphology,  as  elsewhere  indicated,  assimilates  that  lo- 
bule, in  a  functional  point  of  view,  with  the  two  convolu- 
tions bordering  the  fissures  of  Rolando  (asc.  frontal  and 
asc.  parietal). 

The  paracentral  lobule  and  the  two  Rolandic  convolu- 
tions are  characterized  by  the  presence  of  the  giant-cells 
of  Betz.  These  cells,  already  described,1  are  found  in  all 
the  parts  which  are  considered  motor-centres. 

Charcot"  remarks  that  this  fact  is  the  more  interesting 
for  the  reason  that  these  cells  are  found  in  all  the  points 
considered  as  motor-centres,  whatever  may  be  the  mor- 
phological difference  in  the  convolutions.  In  the  dog  they 
surround  the  crucial  furrow. 

Now  it  has  been  for  a  long  time  known  that  the  motor- 
cells  of  the  spine  are  very  voluminous,  whilst  in  the  sen- 
sorial regions  they  are  very  small,  or  medium  sized.  So 
anatomy  as  well  as  physiology   indicates  a  relation  be- 

1  See  page  9,  fig.  1.  -  Loc.  cit.,  p.  29. 


20 


CEREBRAL   CONVOLUTIONS. 


tween  the  size  of  the  cells  and  their  functions.  Where 
there  are  motor-centres  there  are  large  cells  ;  this  is  true 
of  the  cortex  cerebri  as  well  as  of  the  spinal  axis. 

To  this  knowledge  Pierret1  has  added  the  interesting 
fact  that  the  dimension  of  the  'nerve-cell  is  not  only  pro- 
portionate to  its  function,  but  that  it  also  holds  relation  to 
the  distance  to  which  it  must  transmit  the  motor  incita- 
tion ;  that  seems  proven  in  case  of  the  spinal  cord,  and 
perhaps  an  analagous  demonstration  will  be  arrived  at  in 
case  of  the  brain. 

The  large  cells  are  found  more  especially  in  the  zone 
Ammonis  (third  layer),  and  in  the  claustral  zone  (fifth  layer). 
Lewis,  who  has  studied  the  details  of  their  distribution, 
gives  the  following  measurement  : 


In  man- 


Asc.  front. 

Asc.  pariet. 
In  the  cat — Gyrus  sig. 
In  the  sheep — Gyrus  sig. 


CLAUSTRAL  LAYER. 


126  m.  55  m.2 
88  m.  41   m. 

106  m.  32  m. 
65  m.  23  m. 


LAYER    AMMONIS. 


41  m.  23  m. 
51m.  32  m. 
23  m.  13  m. 
18  m.   10  m. 


For  more  details  upon  this  question  we  refer  to  the 
memoir  of  the  author. 

The  motor-cells  seem  to  form  in  groups  in  very  limited 
zones,  with  a  determined  and  constant  situation  in  certain 
points  of  the  cortex  cerebri  ;  each  group  appears  to  be  di- 
vided into  a  series  of  secondary  groups,  which  are  the 
nests  {nids)  described  by  Betz. 

Except  the  great  cell-layers,  the  layers  in  the  motor- 
zones  have  no  special  characteristics  ;  at  all  events,  the 
details  given  by  certain  authors  are  too  accessory  or  too 
uncertain  to  be  mentioned.  I  will  say  the  same  respect- 
ing differences  between  superior  and  inferior  regions  of 
the  same  convolution.3 

As  for  the  cells  of  the  transition-space  between  the  motor 


1  Comptes  rendus  de  l'Acad.  des  sciences,  1878,  1,  p.  1423. 
-  The  two  figures  indicate  the  large  and  the  small  diameters. 
3  See  the  tables  of  Lewis. 


STRUCTURE  OF  THE  CONVOLUTIONS.         21 

and  sensorial  zones,  the  change  is  not  brusque,  and  the 
cells,  though  larger  than  in  the  occipital  lobe,  are  yet 
smaller  than  in  the  convolutions  anterior  to  the  fissure  of 
Rolando.  To  a  certain  degree  the  ascending  parietal  con- 
volutions may  be  considered  as  the  transition  zone.  In 
man,  the  cells  of  that  convolution  measure  : 

At  the  top 88 — 41  m. 

In  the  centre       ....         55 — 32  m. 
At  the  bottom        ....     41 — 24  m. 

To  Lewis'  opinion  may  be  added  that  of  Betz,  who  held 
that  there  were  two  fundamental  regions,  separated  by  the 
fissure  of  Rolando.  Anteriorly  were  the  great-cell,  and 
posteriorly  the  small-cell  convolutions.  Physiology  does 
not  confirm  this  distinction,  for  the  ascending  parietal  con- 
volution, back  of  the  fissure  of  Rolando,  manifestly  belongs 
to  the  motor-region.  In  accordance  with  Lewis,  however, 
this  convolution  can  be  considered  as  representing  a  transi- 
tional zone. 

Occipital  Type. — The  sensorial  (?)  convolutions  em- 
brace :  1  st,  the  cuneus  ;  2d,  the  posterior  half  of  the  lingual 
and  fusiform  lobules  ;  3d,  the  occipital  lobe  ;  4th,  the  first 
two  sphenoidal  convolutions  and  the  marginal  fold.1 

All  these  convolutions  have  a  structure  apparently  differ- 
ent from  the  anterior  parts. 

Vicq  d'Azyr  observed  a  white  band  {ruban  de  Vicq  d'Azyr) 
between  two  gray  layers,  the  whole  constituting  the  gray 
cortex  of  the  posterior  convolutions. 

The  correctness  of  this  observation  has  been  confirmed 
and  perfected  by  modern  researches. 

The  layer  Ammonis  (third)  is  seen  to  be  replaced  by  two 
layers  of  myelocytes  with  fewer  cells,  though  relatively 
voluminous.  The  morphological  modification  of  the  layer 
Ammonis  can  be  otherwise  described  in  saying  that  the 
original  has  disappeared  and  been  replaced  by  the  exten- 
sion of  the  subjacent  granular  layer,  divided  into  three 
secondary  layers,  so  furnishing  eight  layers. 

1  Charcot,  loc.  cit.,  p.  29. 


22 


CEREBRAL   CONVOLUTIONS. 


Clarke  '  takes  the  structure  of  the  occipital  convolutions 
as  his  starting  point  in  the  description  of  the  cortex  cere- 
bri ;  he  recognizes  the  two  granular  zones,  but  makes  no 
difference  between  the  fusiform  and  granular  cells. 

Meynert  found,  in  various  parts  of  the  granular  layers, 
cells  which  he  called  solitary,  and  which  he  deemed  very 
voluminous,  though  they  are  not  so  large  as  the  cells  of  the 
motor-regions.  Probably  they  belong  to  the  pyramidal  type. 

Let  us  now  compare  the  structure  of  the  posterior  sen- 
sorial convolutions  with  that  of  the  retina,  a  sensitive 
expansion  and  in  the  embryo  all  but  an  encephalic  convo- 
lution. 

Owing  to  the  curve  of  the  retinal  layer,  and  to  the  atro- 
phy of  the  posterior  lamina,  which  forms  the  pigmentary 
layer,  the  anterior  lamina  becomes  the  homologue  of  the 
superficial  encephalic  layer,  in  such  way  that  the  most 
superficial  portion  of  the  convolutions  are  morphologically 
represented  by  the  most  profound  layers  of  the  retina, 
those  which  are  in  contact  with  the  vitreous  humor.  We 
can  establish  a  sort  of  parallel  between  these  various  parts, 
and  group  them  thus  ;  of  course,  somewhat  artificially  : 

OCCIPITAL   CONVOLUTIONS. 

External  limiting. 

Represented  by  the  handle- 
fibres  of  Valentin  and 
Kôlliker. 

Pyramidal  layer. 

External  granular  layer, 
which  replaces  the  layer 
Ammonis. 


RETINA. 
Internal  limiting. 
Layer  of  nerve-fibres. 


Layer  of  nerve-cells. 
Layer  of  myelocytes. 


Intermediate  layer. 
Layer  of  myelocytes. 
External    limiting     layer. — 

Exists  in  the    retina  only 

as  a  rudiment. 
Membrana  Jacobi. 


Internal  granular  layer. 


Claustral  layer. 


1  Clarke:   Proceedings  of  the  Royal  Society,  London,  1863. 


STRUCTURE  OF  THE  CONVOLUTIONS.         23 

In  brief,  from  its  structure,  development  and  function, 
the  retina  can  be  regarded  as  an  expansion  of  the  sensorial 
cerebral  cortex. 

Such,  then,  are  the  principal  differences  existing  between 
the  posterior  and  anterior  motor  parts  of  the  cortex  cere- 
bri, and  they  may  be  expressed  in  two  propositions. 

A.  The  motor  regions  possess  giant-cells  located  in  the 
layer  Ammonis  and  throughout  the  claustral  laj^er. 

B.  In  the  posterior  regions  the  layer  Ammonis  is  replaced 
by  a  granulo-glandular  layer. 

We  will  now  examine  the  arrangement  in  some  special 
convolutions.  Meynert  describes  three  distinct  types  : — 
1,  Found  in  the  fissure  of  Sylvius  and  the  Island  of  Reil  ;  2, 
in  the  cornu  Ammonis  ;  3,  in  the  olfactive  bulb. 

Tvpe  of  the  Fissure  of  Sylvius. — The  convolutions 
surrounding  the  fissure  of  Sylvius  are  remarkable  only  for 
the  development  of  fusiform  cells,  which  form  a  deep  claus- 
tral layer,  better  limited  here  than  elsewhere. 

Notwithstanding  its  obscurity,  and  perhaps  because  of 
its  obscurity,  here  arises  an  important  morphological 
question.  The  layer  of  gray  substance,  extended  as  a  little 
band  between  the  lenticular  ganglion  of  the  corpus  stri- 
atum and  the  gray  cortex  of  the  island,  that  which  Mey- 
nert calls  the  "  avant-mur"  has  been  considered  as  a  part  of 
the  cortex  cerebri,  the  claustral  layer  of  the  three  convo- 
lutions of  the  Island.  It  appears  that  in  the  brains  of 
idiots,  the  white  lamina,  which  separates  the  insulary  con- 
volutions from  the  avant-mur,  is  absent,  and  the  avant-mur 
really  becomes  the  internal  layer  of  the  cortex  cerebri 
(Betz).  Now,  according  to  Meynert,  the  structure  of  that 
avant-mur  is  identical  with  the  claustral  layer  ;  there  are 
to  be  found  fusiform  cells,  pressed  one  against  another,  a 
structure  widely  differing  from  that  of  the  gray  ganglion 
of  the  corpus  striatum  and  thalamus  opticus.  To  employ 
Meynert's  expression,  the  formation  belongs,  not  to  the 
central  ganglia  of   the  brain,  but  to  the  system  of  associ- 


24  CEREBRAL   CONVOLUTIONS. 

ation,  which  always  constitutes  the  internal  claustral  layer 
of  the  convolutionary  cortex. 

It  is  here  useless  to  recall  the  arrangement  of  the  cen- 
tral ganglia  relatively  to  the  avant-mnr.  It  is  known 
that  the  external  capsule,  situated  externally  to  the  lenti- 
cular ganglion,  is  divided  by  the  gray  band  (the  avant-mur) 
into  two  parts,  the  external  one  belonging  to  the  cortical 
system,  the  internal,  or  profound,  to  the  central  system. 
Besides,  the  circulation  of  the  avant-mur  is  a  part  of  the 
circulation  of  the  convolutions  of  the  island  and  not  that 
of  the  corpus  striatum.1 

I  will  add  that  this  is  not  admitted  by  all  authors.  Luys 
in  particular  considers  the  avant-mur  a  dependence  of  the 
corpus  striatum.  This  interesting  point  demands  new  re- 
searches, but  I  do  not  believe  the  solution  belongs  to  pure 
anatomy.  Physiology  and  pathological  anatomy  must 
solve  it. 

Some  English  authors  have  studied  the  special  structure 
of  the  insular  convolutions;  especially  Broadbent2  and 
Major.3  The  latter  concludes  that  there  exists  no  funda- 
mental difference  between  the  layers  of  the  island  and 
those  of  the  vertex.  He  has  measured  the  cells  of  the 
island  and  gives  the  following  figures  for  the  various  layers  : 
i.  Ext.  layer,      ....     0.008  to  0.012  mm. 

2.  Pyramidal  layer, 

3.  Layer  Ammonis,     . 

4.  Granular  layer,  . 

5.  Sup.  claustral  layer, 
7.   Profound  claustral  layer, 

The  last  layer  is  generally  composed  of  fusiform  cells. 
The  layer  Ammonis  (third)  is  the  only  one  of  the  island 
which  differs  from  the  same  layer  in  other  convolutions. 

1  Duret  :  Anat.  Researches  upon  Encephalic  Circulation.     Arch,  de  physio!., 

1874,  P-  79- 

'2  Structure  of  the  Cerebral  Hemisphere  (cited  by  Major). 

s  The  Histology  of  the  Island  of  Reil.     West-Riding  Lunatic  Asylum  Med. 
Reports,  t.  vi.,  1876,  p.  1  et  suiv. 


0.012 

"  0.02 

0.020 

"  0.028 

O.OI2 

"  0.024 

0.020 

"  0.024 

0.016 

"   0.02 

STRUCTURE   OF   THE   CONVOLUTIONS.  2$ 

The  cells  contained  therein  are  smaller  than  in  the  frontal 
regions,  which  perhaps  removes  the  island  from  being  in- 
cluded as  a  motor-centre.1 

Type  Hippocampi. — The  study  of  the  cornu  Ammonis 
and  the  gyrus  hippocampi  should  be  made  morphologically 
as  well  as  microscopically,  for  it  is  interesting  to  show  by 
what  modifications  Nature  has  converted  a  normal  convo- 
lution into  an  aberrant  one,  as  in  the  instance  of  the  cornu 
Ammonis. 

To  render  the  structure  of  this  region  comprehensible, 
I  refer  to  the  accompanying  schematic  plates. 

The  transverse  sections  of  Luys,  best  expose  the  cornu 
Ammonis.  Upon  a  brain  hardened  by  alcohol,  or  one 
quite  fresh,  let  the  occipito-sphenoidal  lobe  be  cut  in  paral-. 
lei  slices  commencing  at  the  anterior  extremity,  and  the 
modifications  of  the  cortex  can  be  observed  as  it  becomes 
the  cornu  Ammonis.  This  is  the  process  long  ago  recom- 
mended by  Vicq  d'Azyr.2 

First  is  seen  a  little  gray  band  of  the  outside  cortex 
which  becomes  invaginated,  folds  upon  itself,  whilst  the 
subjacent  white  substance,-  at  first  very  large,  little  by  little 
becomes  thinner,  as  though  the  lateral  ventricle  (V)  pro- 
longed into  the  sphenoidal  lobe  were  about  to  invade 
it.  Gradually  this  white  substance  becomes  thinner  and 
at  last  assumes  the  form  of  a  thin  resisting  lamina,  the  wall 
of  the  lateral  ventricle  and  the  superficial  portion  of  the 
cornu  Ammonis. 

This  is  what  anatomists  term  the  alveolus  (B).  Pro- 
ceeding posteriorly  it  will  be  seen  that,  upon  the  internal 
side  of  the  fold,  this  cerebral  lamina  lessens  in  such  way 
that  finally,  at  the  most  posterior  part,  it  is  reduced  to  sim- 
ply a  thin  layer  of  white  substance,  which  layer,  through 
constant  decrease,  finishes  by  becoming  in  the  lateral  ven- 
tricle entirely  free  from  the  inner  side  and  becomes  the 


1  A  good  plate  is  annexed  to  Major's  memoir. 

2  See  Sappey's  Anat.  desc,  t.  iii.,  p.  105  and  figs.  457,  458,  459. 


26 


CEREBRAL   CONVOLUTIONS. 
Plate  I. 


EXPLANATION   OF  PLATES. 

(cornu  ammonis.) 
Plate  I. — Figs.  I  and  2,  relations  of  the  hippocampus  with  the  lateral  ventricle. 

The  letters  are  the  same  as  for  plate  II. 
Plate  II. — Figs.  1,  2,  3,  4,  5,  6,  7,  8,  9.     (See  next  page.) 

V.  Cavity  of  the  lateral  ventricle. 

A.  Point  where  the  gray  substance  invaginates  to  form  the  hippocampus. 

B.  Lamina  of  the  deep  white  substance  which  tapers  down  to  form  the  ven- 
tricular wall  of  the  cornu  Ammonis  (cuneus). 

S.   Subiculum,  a  white  lamina  originating  in  the  peripheric  gray  substance, 
curving  at  C  so  as  to  form  a  crosier  (bishop's  pastoral  cross). 
To  render  the  figures  more  distinct,  the  corpus  fimbriatum  and  choroid  plexus 
are  suppressed. 


STRUCTURE   OF   THE   CONVOLUTIONS. 
Plate  II.  (Cornu  Ammonis). 


27 


Fig.l. 


Fia.  5. 


Fifl.  2 


Fig.  6. 


Fig.  7. 


B    T 


S  A 


Fig.  3.7T 


28  CEREBRAL   CONVOLUTIONS. 

ribbon  which  anatomists  call  corps  bordant  (the  taenia  hip- 
pocampi). 

Thus  the  lobule  hippocampi  is  first  formed  by  the  fold- 
ing of  the  gray  substance  and  a  more  or  less  voluminous 
vessel  at  its  base  giving  off  twigs  which  penetrate  between 
the  two  gray  laminae  of  the  convolutionary  axis  thus 
formed.  The  presence  of  these  twigs  in  the  brains  of  aged 
subjects  are  of  great  advantage  to  the  observer. 

Following  these  two  layers,  it  is  seen  that  upon  the  peri- 
pheric surface  (now  become  the  central)  of  one  of  them 
appears  a  very  slight  layer  of  white  substance  arising  from 
the  gray  substance  itself  (S).  This  is  described  by  authors 
as  the  subiculum.1 

This  white  layer  is  not  a  dependence  of  the  medullary 
white  substance  of  the  brain,  but  a  dependence  of  the  gray 
cortex  cerebri  from  which  it  originates. 

If  this  were  all,  the  gyrus  hippocampi  would  be  rela- 
tively simple  ;  but  a  new  complication  renders  the  descrip- 
tion somewhat  difficult.  That  gray  lamina,  surrounded  by 
the  alveolus  of  the  internal  or  ventricular  side,  and  by  the 
subiculum  on  the  external  or  peripheric  side,  coils  upon  it- 
self like  the  top  of  the  pastoral  staff  of  a  bishop,  sometimes 
completing  a  circuit  similar  to  the  spiral  or  helix  of  a  snail. 
The  gray  blade  accompanied  by  these  two  white  laminas 
appears  like  a  twisted,  elastic  lamina,  strongly  stretched 
and  fastened  at  one  of  its  edges.  In  the  very  body  of  the 
gray  lamina  there  is  a  very  attenuated  layer  of  white  sub- 
stance, which  can  be  seen  only  with  a  glass  and  which  ap- 
pears to  extend  to  the  extremity  of  the  central  lamina. 

Finally,  to  complete  this  difficult  description,  we  would 
add  that  the  thin  gray  blade  seems  at  its  extremity  to  con- 
tinue directly  with  that  little  reddish  band,  covered  with 
projections  and  called  the  choroid  plexus  (corps goudronné) 

1  It  can  be  very  well  seen  in  the  schematic  figure  given  by  Mathias  Duval, 
art.  Nerfs,  du  Diet,  de  méd.  et  chir.  prat.,  p.  474,  fig.  72. — See  also  in  Traité 
d'anat.  of  Sappey,  fig.  459,  2 — white  lamella  which  separates  the  fimbriated 
body  from  the  gyrus  hippocampi. 


STRUCTURE  OF  THE  CONVOLUTIONS.         29 

which,  with  the  cornu  Ammonis  and  the  taenia  hippocampi, 
jut  into  the  lateral  cavity  of  the  fourth  ventricle.  Lélut. 
quoted  by  Sappey,  makes  the  subiculum  pass  around  the 
choroid  plexus  and  become  confounded  with  the  alveolus.1 

All  these  details  are  somewhat  difficult  to  understand, 
and  I  think  that  they  can  be  followed  only  by  referring  at 
the  same  time  to  the  plates.2  (Cornu  Ammonis,  pp.  26 
and  27.) 

When  the  anatomical  description  is  so  obscure,  it  is  al- 
ways difficult  to  determine  the  minute  structure.  We  are 
indebted  entirely  to  Meynert  for  instructions  upon  the 
structure  of  the  gyrus  hippocampi,  and  these  instructions 
are  not  over-satisfying. 

In  the  cornu  Ammonis  there  exist  only  large  pyramidal 
cells,  and  the  second  layer  is  lacking. 

Also  there  is  an  absence  of  fusiform  cells  (claustral 
layer).  In  other  words,  the  layer  Ammonis  is  larger- 
developed,  and  unaccompanied  by  other  layers. 

Supposing  the  cornu  Ammonis  unfolded,  a  section  would 
discover:  1st,  the  subiculum  with  very  small  nerve-cells 
(homologue  of  the  external  layer)  ;  2d,  the  lacunal  stratum, 
with  a  network  of  pyramidal  prolongations  (homologue  of 
the  pyramidal  layer),  but  where  the  pyramidal  cells  are 
lacking  ;  3d,  the  stratum  radiatum  (homologue  of  the  upper 
layer  Ammonis  ;  4th,  the  pyramids  (homologue  of  the  lower 

1  That  peculiarity,  represented  by  Sappey  (fig.  459,  I.,  2)  has  not  been 
figured  by  Mathias  Duval. 

2  Among  the  atlases  which  I  have  been  able  to  consult  on  this  subject 
{Tiedeman,  Foville,  Hirschfield,  Leuret  and  Gratiolet,  Gall  and  Spurzheim. 
etc.)  none  are  exact  concerning  the  cornu  Ammonis  except  the  works  above 
cited  ;  Sappey,  Anat.  descript.,  t.  iii.,  and  Mathias  Duval,  art.  Nerfs,  p.  474. 
I  will  also  add  :  Wundt,  Physiologische  Pyschologie,  p.  82,  fig.  34.  The 
plates  of  Luys,  Recherches  sur  le  système  nerveux,  1865,  atlas,  pi.  xxi.,  figs.  1,  2, 
3,  4,  5,  6,  are  perhaps  not  very  clear.  On  the  other  hand,  in  his  photographic- 
atlas  the  transverse  sections  (pis.  i.  to  xi.)  show  the  structure  of  the  gyrus  hippo- 
campi with  a  remarkable  clearness  and  exactitude.  I  regret  not  having  been 
able  to  consult  the  work  of  Kupffer,  eulogistically  spoken  of  by  Frey  :  De 
structure  cornu  Ammonis,  Dorpat,  185g.  Microscopically  there  is  a  good  cut 
in  Meynert  (loc.  cit.,  fig.  236). 


30  CEREBRAL   CONVOLUTIONS. 

layer  Ammonis)  ;  5  th,  the  alveolus  (the  homologue  of  the 
projection  of  the  ependyma  ventriculorum).1 

Olfactive  Bulb. — To  these  varieties  of  convolutions 
should  be  added  another,  of  a  special  form,  so  special  as  to 
be  at  first  confounded  with  a  nerve  ;  I  refer  to  the  olfactive 
bulb.  The  olfactive  bulb,  truly  speaking,  is  as  distinct 
from  a  convolution  as  from  a  nerve  ;  it  is  an  organ  by 
itself,  a  kind  of  aberrant  type,  which  can,  however,  thanks 
to  comparative  studies,  through  morphology  and  embry- 
ology, be  classed  under  the  general  type  of  the  peripheral 
gray  cortex.2     Luys  rightly  compares  it  to  the  retina. 

The  olfactive  bulb  is,  in  the  embryon,  a  hollow  organ, 
an  olfactive  vesicle,  the  same  as  there  is  a  retinal  and 
auditory  vesicle.  With  some  animals  this  vesicle  remains 
permanent,  presenting  an  olfactive  ventricle,  lined  with 
vibratory  cells,  the  bases  of  which  are  in  rapport  with  the 
subjacent  nuclei  (myelocytes).3  As  for  the  white  root  of 
the  olfactive  nerve,  that  should  be  considered  as  a  com- 
missure of  the  white  substance. 

In  man,  however,  this  ventricle  does  not  exist.  The 
other  constituents  of  the  olfactive  bulb  have  not  been 
rightly  studied,  and  seem  to  be  ill-known,  though  some 
labors  in  this  direction  have  been  undertaken.4 

The  external  layer  seems  to  be  formed  of  a  white  sub- 
stance containing  pale  nerve-fibres,  without  myéline,  which 
intermix  like  a  network.  Beneath  that  layer  is  a  zone  of 
gray    substance,    which    contains    voluminous    multipolar 

1  These  details  will  not  be  understood,  except  by  following  the  scheme  of 
Meynert,  fig.  237.  loc.  cit. 

2  Broca  makes  two  types  of  mammifera,  according  to  the  volume  of  the  olfac- 
tive lobe  ;  the  horse  and  the  dog,  for  example  (psmatiques),  man  and  monkey, 
anosmatique  or  very  atrophied.  See  Revue  d'anthropologie,  1878,  p.  392 
et  suiv.,  Le  Lobe  olfactive  et  le  sens  de  l'odorat. 

3Owjamniskow  :  Midler's  Arch.,  i860,  p.  54.  Walter:  Virch.  Arch.,  xxii., 
p.  241.     See  also  illustration  of  horse  by  Broca,  loc.  cit.,  Fig.  3. 

4L.  Clarke:  Zeitschrift  fiir  Wiss.  Zoôl.,  xi.,  p.  31.  Schultze,  quoted  by 
Kôlliker,  Element,  d'histol.,  p.  961.  Golgi  :  Ricerche  sulla  fina  struttura  dei 
bulbi  olfactorii,  Reggio,  1875.     Meynert  :  loc.  cit.,  t.  x.,  p.  102. 


STRUCTURE  OF  THE  CONVOLUTIONS.         3 1 

cells  and  some  peculiar  bodies,  globular  in  form,  first 
described  by  Leydig  as  found  in  fish,  then  by  Schultze 
Golgi,  and  others  under  the  name  of  glomeruli  ;l  they  seem 
to  be  only  a  mass  of  ganglionic  cells'2  (Schultze,  Kôlliker). 
Meynert's  term  of  stratum  glomerulosum  may  be  accepted. 
There  is  then  a  second  layer,  which  embraces  superficially 
the  glomeruli,  and,  deeper  down,  the  large  nerve-cells, 
analogous  to  the  cells  of  Purkinje,  in  the  cerebellum. 
Between  these  two  ranges  of  cells  are  found  axis-cylinders, 
serving  probably  to  connect  them.  Besides  this,  these 
cells  give  out  prolongations,  which  connect  equally  with 
each  layer,  both  of  which  layers  are  essentially  composed 
of  the  fasciculi  of  the  olfactive  nerve.  In  the  deep  layer 
there  are  also  pyramidal  cells  with  prolongations,  which 
may  be  traced  to  the  nerve-cells  and  to  the  glomeruli  of  the 
middle  layer. 

Nothing  is  less  elucidated  than  the  structure  of  the 
olfactive  bulb  (olfactive  convolution,  or,  still  better,  olfac- 
tive lobe).  New  researches  are  necessary.  We  will  con- 
tent ourselves  with  the  establishment  of  two  facts — about 
the  only  things  at  present  positively  known  respecting  that 
obscure  part  of  the  cerebral  structure:  1st,  the  olfactive 
nerve-fibrillae  divide  and  anastomose  in  a  network  ;  2d, 
they  are  in  rapport  with  the  nerve-cells  and  the  special 
cells  of  the  second  layer  of  the  olfactive  bulb  {Glomeruli  of 
Golgi).3 

1  This  is  what  Pouchet  and  Tourneux  call  the  spheric  mass  of  gray  substance 
(loc.  cit.,  p.  587). 

2  See  Meynert,  fig.  240.     The   vessels  which  go  to  the  glomeruli  are  shown. 

3  Among  the  different  works  undertaken  upon  the  structure  of  the  gray  cor- 
tex I  will  cite  that  of  Major,  especially  interesting  in  an  anatomico-pathologi- 
cal point  of  view  :  "  On  the  minute  structure  of  the  cortical  substance  of  the 
brain."  West-Riding  Lunatic  Asylum  Reports,  1872,  page  41,  and  various 
articles  published  in  these  reports  and  in  The  Lancet  (21st  July,  1877).  The 
work  of  Lubimoff  ought  also  to  be  noted  (Arch,  de  physiol.) 


32  CEREBRAL   CONVOLUTIONS. 


Sec.  6.  STRUCTURE  OF  THE  GRAY  SUBSTANCE 
OF  THE  CONVOLUTIONS  OF  MAMMIFERA. 

Here  again  the  details  are  few,  and  information  can  be 
found  only  in  the  writings  of  Meynert,1  Major,2  and  Lewis. 

Among  various  animals  there  exists  considerable  differ- 
ence ;  the  layers  thus  far  spoken  of,  however,  always  exist 
and  are  tolerably  well  outlined,  as  shown  in  Lewis'  plates 
of  the  cat  and  sheep,4  the  only  specimens  perhaps  which 
have  been  given  of  the  convolutions  of  mammifera.  In 
one  of  Luys'  unpublished  photographs  of  the  convolutions 
of  a  pig,  the  external  limiting  layer — that  which  is  poor  in 
cells,  and  perhaps  of  a  conjunctive  nature — is  very  thick, 
and  the  layers  to  which  the  nerve-cells  belong  occupy  not 
more  than  two-thirds  of  the  gray  cortex  ;  the  claustral  layer 
is  seen  to  be  also  very  thick. 

But  there  is  not  much  interest  in  stating  that  this  or 
that  layer  of  cells  has  greater  or  less  thickness,  or  differ- 
ent lengths  of  prolongations  in  different  animals.  Besides, 
it  has  been  little  studied,  and  it  is  only  known  that  the 
differences  are  nearly  always  confined  to  the  occipital 
lobes. 

On  the  contrary,  the  structure  of  the  cerebral  cortex  of 
the  monkey  has  a  great  interest.  In  comparing  it  with 
the  human  cortex,  we  may  hope  in  a  certain  degree  to  find 
a  reason  for  the  enormous  difference  of  intelligence,  or  at 
least  without  adventurous  hypothesis  to  establish  a  com- 
parison between  the  absence  or  the  increase  of  volume  of 

1  Strieker's  Handbuch,  etc.,  loc.  cit. 

-  Observations  upon  the  brain  of  the  Chacma  Baboon  (Cynocephalus  Porca- 
rius,  Journal  of  Mental  Science,  Jan.,  1876,  p.  502.  This  memoir  is  very  re- 
markable and  interesting. 

3  Loc.  cit. 

4  Loc.  cit.,  plates  2  and  3. 


STRUCTURE  OF  THE  CONVOLUTIONS.         33 

certain  cells,  as  accompanied  by  the  diminution  or  increase 
of  intelligence. 

Major  has  studied  successively  the  number  and  the  ap- 
pearance of  the  layers,  the  general  character  of  the  nerve- 
cells  and  their  prolongations,  and  the  number  of  these 
prolongations.  The  following  are  his  principal  conclu- 
sions : 

1st.  In  monkey  and  man,  the  number  and  the  relative 
dimensions  of  the  cortical  layers  are  nearly  identical. 
There  is  no  difference  as  to  the  intimate  nature  of  the 
cells,  and  their  reactions  are  identical. 

2d.  All  the  layers  of  cells  are  similar,  save  the  second 
one  in  the  frontal  convolutions,1  where  in  man  there  abound 
large  cells,  whilst  in  the  monkey  they  are  rare.  Major 
supposes,  and  not  without  some  likelihood,  that  there  is 
a  relation  between  the  volume  and  number  of  these  cells 
in  man,  and  the  faculty  of  language  special  to  man,  and 
localized  in  the  frontal  lobes.  Moreover,  it  seems  that 
old  age  and  intellectual  enfeeblement  in  man  coincides 
with  degeneration  of  the  large  cells,  so  that  their  paucity 
of  numbers  in  the  Chacma  baboon  would  be  a  sign  of 
inferiority. 

As  a  rule,  the  number  of  the  prolongations,  and  conse- 
quently the  sphere  of  action  of  each  cell,  is  considerably 
greater  in  man. 

Major  has  also  studied  the  senile  alterations  of  the 
nerve-elements  of  the  convolutions  of  animals,  and  he  in- 
sists upon  the  pigmentary  degeneration  of  the  nerve-cells. 

'Major  says  the  second  layer,  p.  510.  It  seems,  however,  that  the  large 
cells  belong  rather  to  the  third  layer  (Ammonis). 

a  On  the  Morbid  Histology  of  the  Brain  in  the  Lower  Animals.  West-Riding 
Lunatic  Asylum  Reports,  1875. 


34  CEREBRAL   CONVOLUTIONS. 


Sec  7.  WHITE  SUBSTANCE  OF  THE  CONVO- 
LUTIONS. 

We  now  pass  to  the  study  of  the  white  substance  of  the 
convolutions,  and,  as  with  the  gray  portion,  we  will  not 
give  a  general  description,  but  of  that  only  which  is  im- 
mediately subjacent  to  the  gray  cortex,  and  which  forms 
the  axis  of  the  convolutions. 

It  was  the  ancient  idea  that  the  cerebral  convolutions 
were  the  result  of  a  doubling-up  of  a  peripheric  layer,  for 
Sténon  strongly  protested  against  that  idea  and  that  error 
of  anatomists.  "  There  are  those  who  would  even  have  us 
take  the  substance  of  the  brain  for  a  membrane."1 

Long  time  after  that,  the  same  idea  was  entertained  by 
Gall,  who  thus  expresses  himself  : — "  Each  convolution 
consists  of  two  fibrous  layers  which  are  entirely  covered 
by  a  gray  layer  of  nearly  uniform  thickness.  The  laminas 
of  the  cerebellum  are  formed  in  the  same  way.  The  two 
fibrous  layers,  formed  by  the  ascending  and  diverging 
fasciculi,  are  accompanied  also  by  fibres  which  come  from 
the  gray  substance,  so  that  each  convolution  is  composed 
of: — 1st,  very  fine  re-entering  nerve-fibres;  2d,  fibres  of 
the  diverging  fasciculi  ;  3d,  the  exterior  envelope  of  gray 
substance.  It  is  this  arrangement  which  renders  it  pos- 
sible to  separate  the  two  layers  of  fibres  without  injury  to 
them,  and  to  stretch  out  a  surface  and  unfold  each  convo- 
lution or  duplicature."2 

That  idea  of  Gall's  is  perhaps  exact,  but  modern  re- 
searches certainly  are  based  upon  different  processes,  and 
notwithstanding  that  the  microscope  has  furnished  better 


1  Anatomical  Exposition  of  the  Structure  of  the  Human  Brain,  Winslow, 
Amsterdam,  1752,  t.  iv.,  p.  210. 

2  Anat.  et  phys.  du  syst.  nerveux,  1810,  t.  i.,  p.  299. 


STRUCTURE  OF  THE  CONVOLUTIONS.         35 

grounds  for  judgment,  the  question  is  still  environed  with 
uncertainties. 

The  opinion  of  Meynert,  adopted  by  Charcot,  and  the 
correctness  of  which  seems  very  probable,  is  known.  It 
holds  the  periphery  of  the  brain  to  be  a  system  of  projec- 
tion. As  in  descriptive  geometry,  a  projection  can  be  made 
from  the  surface  of  a  solid,  so  the  cortex  cerebri  is  the 
projection  of  the  nerve-fibres  contained  in  the  ganglionic 
centres  of  the  encephalon.  To  this  must  be  added  that 
these  centres  furnish  a  system  of  condensation,  since  the 
number  of  optico-strio-medullary  fibres  is  much  less  than 
the  optico-strio-cortical  fibres.  Besides  this,  Meynert  has 
described  a  system  of  association  formed  by  anastomosing 
fibres  which  unite  the  various  convolutions  and  establish 
between  them  a  complete  and  harmonious  consensus. 

These  ingenious  views  are  but  hypothetical  ;  and  it  must 
be  said  that,  to  the  present,  anatomical  observations  of 
the  cerebral  structure  have  never  passed  the  domain  of 
hypothesis  ;  we  again  repeat,  that  only  physiology  and 
pathological  anatomy  are  capable  of  judging  the  relations 
between  the  convolutions  and  the  nerve-axis. 

It  should  be  observed  that  Baillarger  has  long  since 
described  two  rows  of  vertical  fibres  in  the  axis  of  the  con- 
volutions (in  the  dog  and  rabbit),  crossed  by  transverse 
fibres. 

The  schemes  constructed  by  Luys  must  also  rank  as 
hypothetical.  That  eminent  anatomist  has  dt^/ibed  the 
relations  of  the  various  convolutions  with  each  other  and 
with  the  central  ganglia.  In  the  majority  of  his  conclu- 
sions, Luys  has  certainly  arrived  at  the  same  results  as 
have  pathologists  ;  but  as  it  is  the  result  of  pathology 
which  alone  carries  conviction,  we  will  further  along  return 
to  what  we  have  to  say  respecting  cortical  degenerations. 

The  knowledge  derived  by  the  microscope  is  scanty  and 
inconclusive. 

It  is  known  that  the  white  substance  is  composed  of 
cylinder-axes  surrounded  by  myéline,  and  it  may  be  antici- 


36  CEREBRAL   CONVOLUTIONS. 

pated  that  an  attempt  has  been  made  to  establish  a  relation 
between  these  cylinder-axes  and  the  cells  of  the  cortical 
layers. 

The  first  point  is  still  scarcely  known.  We  have  before 
seen  the  opinion  of  Koschewnikoff  ;  that  opinion  is  very 
clear  and  probable,  though,  as  yet,  undemonstrated. 

According  to  Gerlach,1  these  nerve-fibres  penetrate  the 
nerve-substance,  and  there,  losing  their  myéline,  form  a 
very  fine,  richly  anastomosing,  fibrillous  network,  which 
fibres  have  cellular  terminations.  The  existence  of  this 
network  was  not  universally  admitted.  Rindfleisch  denied 
its  existence.'2  He  maintained  that  after  a  series  of  di- 
chotomous  divisions,  the  nerve-tubes  separate  into  bundles 
and  fibrils  ;  these  fibrillar  go,  some  to  the  nerve-cells,  and 
others  to  the  myelocytes.3 

He  asks  if  these  nuclei  may  not  be  of  nerve-origin,  thus 
indirectly  putting  in  doubt  the  teaching  of  the  German 
school  relative  to  the  interstitial  conjunctive  tissue. 

Prior  to  these  two  authors,  Kolliker  had  given  the  exact 
relation  between  the  nerve-filaments  and  the  cells.4 

It  must  not  be  supposed  that  all  these  observations  are 
easy  to  repeat,  and  Vulpian  rightly  insists,  in  this  question 
more  than  in  any  other,  upon  a  rigid  anatomy,  which  will 
not  be  content  with  approximative  results  and  which  will 
not  affirm  when  there  remains  a  doubt.5 

According  to  Kolliker  the  fibres  do  not  all  penetrate 
directly  into  the  gray  substance,  there  are  those  which 
course  along  the  cerebral  cortex,  forming  as  it  were 
arches. 

In  the  white  substance  of  the  convolutions,  there  exist 

1  Centralbt.  fiir  d.  med.  Wiss.,  1873,  No.  18,  p.  273. 

2  Centralbt.  fiir  d.  med.  Wiss.,  1872,  No.  18,  p.  277. 

:i  Luys  had  already  described  the  connection  of  the  myelocytes  with  the 
nerve-fibres  :  Atlas,  1865,  pi.  xx.,  fig.  5. 

4  See  des  Elém.  d'histol.,  French  trans'.,  p.  401. 

5  Leçons  sur  la  phys.  du  syst.  nerv.,  186S.  For  the  inter-relations  of  nerve- 
fibres,  the  excellent,  though  schematic  design  of  Henle  may  be  consulted. 
Hand,  fiir  Nervenlehre,  1871,  fig.  203,  p.  275. 


STRUCTURE  OF  THE  CONVOLUTIONS.         37 

also  nerve-cells  which  have  been  described  by  Mierzejew- 
ski ■  and  previously  by  Meynert."  These  ceils  are  small, 
from  0.007  mm-  to  0.010  mm.,  and  multipolar;  their  poles 
are  very  long  ;  they  probably  are  cylinder-axes.  Of  the 
nature  of  these  elements  Mierzejewski  is  yet  uncertain. 
They  are  confined  to  the  gray  substance  with  which  they 
perhaps  ought  to  be  classed. 

Their  nuclei  are  very  manifest  and  easily  colored  by 
picrocarmate  of  ammonia. 

If  we  now  compare  the  convolutional  structure  of  the 
cerebrum  with  that  of  the  cerebellum,  it  will  be  seen  that 
they  appear  to  be  constructed  upon  the  same  plan.  There 
is  only  this  difference,  that  the  deep  layers  of  the  cere- 
brum are  more  complex  and  separated  with  tolerable 
distinctness  ;  whilst  in  the  cerebellum,  the  nuclei,  the 
nerve-cells,  and  the  cylinder-axes  are  confounded  in  the 
formation  of  the  internal  or  rust-colored  layer  (Kolliker). 
Thus  we  have  the  following  homologue,  somewhat  sche- 
matic: 

CEREBRUM.  CEREBELLUM. 

Ext.  limiting  layer.  (  Ex.    limiting    layer, 

Pyramidal  layer.  Gray  layer.  1      Layer  of  the  cells 

Amnionic  layer.  (      of  Purkinge. 

Granular  layer.  i  Myelocytes 

Claustral  layer.  Rust-colored  layer.  1     and  nerve- 


cells. 


T   ,    v     ...       ,  ]  Stretched    network  with   quadran- 

int.  limiting  la37er.     i  ,,  ,  , 

(      gular,  parallel  meshes. 

Perhaps  the  corpora  quadrigemina,  or  at  least  their  super- 
ficial portions,  should  be  ranked  with  the  gray  cerebral 
cortex,  though  it  has  not  yet  been  done.  Although  with 
fishes,  birds,  etc.,  the  corpora  quadrigemina  are  developed 
to  the  extent  of  veritable  lobes,  still  in  the  human  subject, 


1  Loc.  cit.,  p.  202. 

2  Strieker's  Handbuch  fur  Geweblehre,  1870,  p.  709. 
4 


38  CEREBRAL   CONVOLUTIONS. 

they  are  very  reduced  ;    in  no  case  presenting  folds  and 
convolutions  and  their  structure  is  very  simple.1 


Sec.  9.     VESSELS  OF  THE  CONVOLUTIONS. 

The  arrangement  of  the  circulator)7  apparatus  in  the 
surface  of  the  nervous  system,  apparently  so  well-known, 
is  really  still  quite  obscure,  since  upon  certain  points  there 
is  complete  discord. 

For  the  historical  part,  we  turn  to  the  work  of  Duret,2 
where  the  question  is  treated  of  in  a  very  complete  manner. 

We  first  observe  that  the  gray  substance  of  the  convolu- 
tions is  much  richer  in  vessels  than  the  white,  illustrated 
by  the  following  cut  borrowed  from  Gerlach.  This  is  a 
well-known  general  fact  and  which  applies  to  the  spinal 
cord  as  well  as  to  the  cortex  cerebri. 

The  gray  cortex  is  so  vascular  that  Ruysch  considers  it 
a  sort  of  arterial  plexus. 

Upon  an  injected  brain  may  be  seen  an  infinite  number 
of  minute  branches  which  fall  like  a  shower  of  rain,  per- 
pendicularly, from  the  pia  mater  into  the  cerebral  sub- 
stance. These  are  the  terminal  arteries  :  they  may  be 
divided  into  two  groups:  one,  very  long  and  voluminous, 
penetrates  through  the  gray  layer  and  into  the  white 
substance  ;  these  are  the  medullary  arteries  :  the  other, 
smaller  (cortical  arteries)  and  much  more  numerous,  appear 
to  be  distributed  in  a  uniform  manner  to  the  gray  layer. 
Between  all  these  branches  there  is  a  rich  network  of 
anastomoses. 

According  to  Duret,  from  whom  we  borrow  these  de- 
tails,3 these  arborescences  of  the  gray  cortex  are  responded 

1  According  to  Serras,  Anat.  comparée  du  cerveau,  Paris,  t.  ii.,  p.  277,  the 
surface  of  the  optic  lobes  are  formed  of  alternate  gray  and  while  layers. 

2  Recherches  anatomiques  sur  la  circulation  de  l'encéphale.  Historique,  p. 
343  et  suiv.,  Arch,  de  physio!.,  1874.  3  Loc.  cit.,  p.  334. 


STRUCTURE  OF  THE  CONVOLUTIONS. 


39 


to  by  similar  arborizations  from  the  pia  mater,  from  which 
it  may  be  inferred  that  all  the  vessels  ramify  before  send- 


ing branches  to  the  brain. 


Layers. 


Fig.  5  (After  Gerlach). — Portion  of  injected  sheep's  brain,  showing  the  dif- 
ference in  the  vascularity  of  the  gray  (a)  and  white  {b)  substance. 

In  a  section  of  vascular-injected  convolution,  the  capil- 
lary network  seems  to  have  four  different  grades. 

f  Pyramidal  ]  Very  rich,  irregular    poly- 

Ammonic'  gonal   network.     This  is 

Granular  the  vascular  region  of  the 

[  Claustral  superf.  encephalon. 

i  Transition  network,  less  rich  than 
Deep  claustral  layer.  \      the  preceding  and   richer   than 

the  subjacent. 

(  Network,  with  meshes  three   or  four 
')      times  larger. 

The  veins,  like  the  arteries,  may  be  divided  into  medul- 


White  substance. 


40 


CEREBRAL   CONVOLUTIONS. 


lary  and  cortical.     The  medullary  veins  do  not  follow  the 
exact  course  of  the  medullary  arteries. 

According  to  Duret,  they  communicate  with  the  veins 
of  the  base  and  of  the  ventricle  of  the  brain,  especially  with 
the  vena?  Galeni.  The  cortical  veins  are  larger  and  less 
numerous  than  the  corresponding  arteries.1 


Arteries  of  the  cortex, 
or  grey  substance 


,  ..Medullary 
'  Arteries 


Arteries  of  the  commissural 
fissure  of  Graholet. 


Fig.  6 — Circulation  in  the  convolutions  (after  Duret). 

It  seems  probable  that  there  are  no  canals  of  communi- 
cation between  the  arteries  and  veins  of  the  gray  cortex 
other  than  the  capillaries. 


1  See  Duret  (loc.  cit.,  p.  338),  who  has  studied  the  question  with  minute  care. 
Charcot  (Leçons  sur  les  Localisations,  1876,  p.  54)  has  shown  that  Hubner's 
researches  on  the  subject  were  absolutely  simultaneous  and  not  posterior,  hav- 
ing been  communicated  upon  the  same  day  (7th  Dec,  1872),  a  portion  to  the 
Biological  Society,  and  a  portion  to  the  Centralblatt  fur  med.  Wissenscli. 


STRUCTURE  OF  THE  CONVOLUTIONS.         4 1 

Regarding-  the  pia  mater  the  question  is  still  under  dis- 
cussion ;  the  objections  of  Duret  to  the  theory  of  Ecker 
and  Sucquet,  which  admits  derivative  canals,  seems  to  me, 
however,  very  serious.  As  with  all  questions  in  dispute, 
the  subject  requires  new  researches.1 

An  interesting  thing,  from  various  points  of  view,  is  the 
relative  independence  of  the  different  vascular  territories 
of  ffrav  cortex  cerebri.2 

Determined  more  especially  by  pathology,  Duret  and 
Charcot  hold  that  there  are  two  very  distinct  regions  in  the 
distribution  of  the  cerebral  arteries  :  the  cortical  region  and 
the  central  {corps  opto-stric's).  "  These  two  systems,"  says 
Charcot,  "  although  common  in  origin,  are  entirely  inde- 
pendent of  each  other,  and  at  their  peripheries  they  have 
no  point  of  communication." 

Not  only  is  there  no  communication  between  the  corti- 
cal and  medullary  systems,  but  the  various  divisions  of  the 
cortical  system  do  not  intercommunicate  except  by  very 
fine  capillaries,  so  that  the  independence  of  the  several 
cortical  regions  is  nearly  complete. 

Duret  says  3  "  that  in  man,  the  dog,  and  the  rabbit,  there 
are  three  separate  regions,  each  furnished  by  a  special 
artery  ;  the  anterior  cerebral  arteries  supply  the  frontal 
lobes,  the  sylvian  (median)  arteries  the  convolutions  about 
the  fissure  of  Rolando,  and  the  posterior  cerebral  arteries 
the  occipital  lobes." 

Cadiat  opposes  various  objections  to  the  views  of  Duret,1 
the  most  important  on.e  seems  to  be  that  in  making  even  a 
gentle  injection  into  any  branch  of  the  arterial  hexagon 
(circle  of  Willis),  the  entire  lobe  becomes  injected,  but  it 
must  be  observed  that  Duret  and  Cadiat  do  not  absolutely 


1  According  to  Heubner  and  Cadiat,  there  should  be  anastomoses  between  the 
veins  and  arteries  of  the  pia  mater. 

2  See  fifth  and  sixth  Lessons  upon  Les  Localisations  du  cerveau,  by  Charcot. 
Part  I.,  1876,  p.  53  et  seq. 

3  Revue  des  Soc.  méd.,  t.  x.,  1877,  P-  42$. 

4  Bull,  de  la  Soc.  de  Biol.,  1S76,  p.  342. 


42  CEREBRAL   CONVOLUTIONS. 

differ,  for  Duret  does  not  deny  anastomoses  of  the  arteri- 
oles of  either  the  pia  mater  or  the  brain  ;  he  only  contends 
that  their  diameters  do  not  exceed  one-fourth  of  a  milli- 
metre, whilst  Cadiat  and  Huebner  allow  them  one  full  mil- 
limetre. It  then  is  but  a  difference  of  degree,  and  the  ques- 
tion is  evidently  difficult  to  settle,  for  an  arterial  injection 
always  distends  the  capillaries. 

In  short,  to  Duret  the  anastomoses  are  not  important, 
to  Cadiat  they  are.  The  matter  is  still  undecided  ;  the 
mode  of  operation  and  the  kind  of  injection  employed  have 
greatly  to  do  with  the  affair.  I  would  add,  however,  that 
the  exact  limitation  of  cerebral  infarctus  and  embolism 
lends  a  certain  degree  of  support  to  Duret's  theory. 

I  will  say  a  few  words  only  concerning  the  structure  of 
the  cerebral  arterioles.  It  is  known  that  Robin  has  pro- 
ven that  the  cerebral  capillaries  are  surrounded  with  a 
lymphatic  sheath.1 

That  sheath  is  studded  with  ovoid  nuclei  ;  it  has  a  thick- 
ness of  o.ooi  mm.  to  0.002  mm.,  and  completely  surrounds 
the  vessel  in  such  a  way  that  two  concentric  tubes  may 
be  seen,  each  containing  different  liquids. 

The  internal  tube  contains  red  globules  ;  the  external, 
leucocytes.  As  yet  it  is  by  no  means  proven  that  these 
canals  are  lymphatic,  inasmuch  as  they  have  never  been 
injected  or  traced  immediately  to  a  ganglion. 

German  anatomists  have  met  this  proposition  with  a 
multitude  of  conjectures  (cellular-perilymphatic  spaces, 
cellular  perivascular  sheaths,  etc.).  Some  histologists  have 
even  thought  these  canals  to  be  pathological  alterations 
(Kesteven  2).  But  as  we  have  not  general  anatomy  under 
consideration,  it  suffices  to  note  the  existence  of  a  lympha- 
tic sheath  to  the  blood-capillaries,  as  if  the  cerebral  tissue 
were  too  delicate  to  endure  the  immediate  contact  of  the 
blood. 

1  For    the   complete   bibliography  see    Riedel  :  Die  Perivasculare  Lymph- 
râume,  Arch,  filr  mik.  Anat.,  t.  xi.,  1875. 
2 Brit.  Med.  Jour.,  June,  1874,  p.  840. 


STRUCTURE  OF  THE  CONVOLUTIONS.         43 


Sec.  8.  DEVELOPMENT  OF  CONVOLUTIONS. 

Notwithstanding  the  considerable  number  of  authors 
who  have  written  upon  the  anatomy  of  the  nervous  sys- 
tem, the  development  of  the  convolutions,  structurally,  not 
morphologically,  has  received  the  attention  of  but  few. 

Until  the  third  month,  as  Tiedemann  *  has  observed,  the 
surface  of  the  hemispheres  is  smooth,  without  fissures  or 
convolutions.  According  to  both  Tiedemann  and  Duret,a 
the  first  cerebral  folds  appear  at  about  the  third  or  fourth 
month.  The  first  fissure  is  not  that  of  Rolando  or  Syl- 
vius, as  the  plates  of  Leuret  and  Gratiolet 3  would  seem  to 
to  indicate,  but  the  external  perpendicular  fissure.4 

Until  the  fifth  or  sixth  month,  there  is  scarcely  any 
development  of  true  convolutions.  Gratiolet  has  repre- 
sented the  brain  of  a  five-months  and  a  half  fœtus,5  which 
is  entirely  analogous  to  an  accompanying  illustration  of 
the  brain  of  a  stupid  monkey.  There  are  incisions,  shal- 
low fissures,  outlining  of  lobules,  or  groups  of  lobules  ; 
but  there  are  no  true  convolutions,  intermixed,  compli. 
cated,  and  with  blunt  angles  as  in  adult  brains.  Even 
with  new-born  children  6  the  convolutions  are  very  simple, 
so  that  they  continue  to  form  after  birth  ;  the  sulci  deepen, 
new  marginal  gyri  appear.  In  a  word,  the  convolutions 
seem  obstructed,  mal- arrêtées,  to  use  Parrot's  expression.7 
It  is  probable  that  these  exterior  differences  correspond  to 


1  Anat.  du  cerveau,  trad,  de  Jourdan,  Paris,  1823,  p.  36,  pi.  I. 

2  Bull,  de  la  Soc.  de  Biol.,  in  Gaz.  méd.,  1877,  p.  172. 

3  Anat.  comp.  du  syst.  nerv.,  Paris,  1839-57,  pi.  xxix.,  figs.  3,  4,  5. 
4 See  also  Duval,  in  Gaz.  Med.,  1877,  p.  161. 

5  Mém.  sur  les  plis  cereb.  de  l'homme  et  des  primates,  p.  82.  Atlas,  pi.  xi., 
fig-.  1.  2,  3- 

6  Leuret  and  Gratiolet,  loc.  cit.,  pi.  xx.,  fig.  2. 

1  Etude  sur  le  ramollissement,  etc.,  Arch,  de  Phys.,  1S73,  p.  63. 


44  CEREBRAL   CONVOLUTIONS. 

differences  of  structure,  but  this  point  does  not  seem  to 
have  been  studied. 

The  first  attempt  seems  to  have  been  made  by  Tiede- 
mann,1  who  wrongly  supposed  that  the  cortical  substance 
was  secreted  by  the  pia  mater  upon  the  surface  of  the 
brain  after  birth.  But  Baillarger2  has  shown  that,  in  the 
human  foetus  of  four  or  five  months,  there  already  exists  at 
the  periphery  a  very  thin  layer  of  gray  substance,  showing 
several  concentric  zones,  alternately  opaque  and  trans- 
parent. 

According  to  Duret,3  from  the  seventh  to  the  ninth 
months,  whilst  the  convolutions  are  forming,  there  appear, 
on  the  one  hand,  nerve-tubes  which  reach  the  superficial 
portion  of  the  cerebral  hemispheres,  and,  on  the  other 
hand,  the  nerve-cells  in  the  cortex.  It  is  not  until  this 
period  also  that  the  arteries  develop. 

Duret  considers  the  coincident  development  of  the  nerve- 
cells,  vascularization,  the  ascent  and  development  of  the 
peduncular  expansion  and  the  appearance  of  the  convo- 
lutions to  prove  that  the  cortex  does  not  acquire  func- 
tional properties  until  towards  the  end  of  fcetal  life.  Phy- 
siology has  arrived  at  a  similar  conclusion. 

Lubimoff  (of  Moscow)  has  arrived  at  analogous  results. 
The  nerve-cells  of  the  cerebrum  and  cerebellum  develop 
last,  whilst  the  cells  of  the  spinal  cord,  and  especially  those 
of  the  great  sympathetic,  develop  much  more  rapidly. 

Mierzejewski4  holds  that,  in  the  white  substance  of  the 
newly-born,  among  the  axis-cylinder,  may  be  found  amoe- 
boid cells  (which  are  colored  black  by  osmic  acid),  polygo- 
nal cells  and  small,  ovoid,  flat  cells.  To  explain  the  rôle 
which  he  assigns  to  these  elements,  it  would  be  necessary 
to  enter  into  the  history  of  the  development  of  nerve-tissue. 

1  Loc.  cit.,  p.  87. 

'-'  Mémoire  sur  la  formation  des  centres  nerveux.     Jour.  l'Esculape,  1840,  et 
Mém.  de  l'Acad.  de  Méd.,  1840,  p.  150  et  suiv. 

3  Bull,  de  la  Soc.  de  Biol.,  in  Gaz.  Méd.,  1877,  !'•  I72- 
4^Loc.  cit.,  p.  202. 


STRUCTURE  OF  THE  CONVOLUTIONS.         45 

Respecting  the  development  of  the  gyrus  hippocampi, 
Duret,  who  made  observations  upon  a  four-months'  foetus, 
says  that  it  is  simply  a  folded  convolution,  which  projects 
underneath  the  corpus  callosum.  Anteriorly  this  convo- 
lution disappears,  little  by  little,  but  posteriorly  it  remains, 
as  before  observed,  and  folds  back  upon  itself.  In  the 
large  work  of  Mihalkowitz  ]  are  to  be  found  details,  too 
long  and  unimportant  to  engage  our  attention,  and  the 
plates  are  also  difficult  to  comprehend.  Flechsig,  in  his 
great  work  on  the  nervous  system,  does  not  dwell  upon 
the  stratification  of  the  layers  ;  he  describes  the  relations 
of  the  various  fasciculi  of  nerve-fibres,  and  thinks  that  the 
white  substance  is  developed  very  late  in  the  embryonic 
convolutions;  in  other  words,  that  Meynert's  "système 
d'association"  becomes  established  only  at  birth.2  This  is 
pretty  much  Duret's  conclusion. 

There  are  two  other  interesting  facts  to  be  added  to  the 
little  which  is  known  upon  the  development  of  convolu- 
tions. First,  the  existence  of  "transitory  convolutions" 
found  in  the  embryon  of  four  or  five  months,  and  which 
disappear  towards  the  seventh  or  eighth  months.3 

Second,  Major,4  who  examined  the  cortical  nerve-cells 
of  an  eight-months'  foetus,  reports  the  almost  complete 
absence  of  cellular  prolongations,  so  that  the  cells  have 
the  appearance  of  round  cells.  Perhaps  the  nerve-cells 
(motor  or  sensorial)  only  develop  with  the  commencement 
of  functional  action.  It  also  appears  that  the  nerve-pro- 
longations become  lost  in  advanced  age. 

It  would  be  an  interesting  study  to  ascertain  at  just  what 
time  the   large  motor-cells  first  appear.     1  have  not  had 

1  Entwickelungs-Geschichte  des  Gehirns,  Leip.,  1877,  p.  145  et  suiv.,  pi.  xx., 
xxi. 

2  Die  Leitungsbahne  im  Gehirn  und  Riïckenmarke  des  Menschen.  Leip. . 
1S76,  in  Jahresber.  fiir  Anat.,  1876,  p.  275. 

3  Milhalkowitz,  loc.  cit.,  p.  144.  Ecker  :  Arch,  fiir  Anthrop.,  1868,  t.  iii. 
His  :  Entwickelungs-Geschichte  der  Grossgehirnhemisphàren.  Sitzber.  der 
Nat.  Gesellschaft  in  Leipzig,  1874,  p.  1. 

4  Loc.  cit.,  Jour,  of  Mental  Science,  p.  511. 


40  CEREBRAL   CONVOLUTIONS. 

time  to  undertake  it.  I  would  observe,  however,  that,  in 
a  cat  one  month  old,  I  have,  in  company  with  M.  Tourneux, 
noticed  that  there  was,  even  at  that  age,  a  difference 
between  the  anterior  and  posterior  cortical  cells,  the  latter 
being  a  little  smaller.  Betz  says  that  giant-cells  do  not 
exist  in  the  new-born. 


PHYSIOLOGY   OF   THE   CONVOLUTIONS.  47 


SECOND   PART. 
PHYSIOLOGY  OF  THE   CONVOLUTIONS. 

ANATOMICAL   INTRODUCTION. 

Although  the  topography  of  the  cerebral  convolutions  is 
known,  still  a  short  anatomical  review  may  not  be  useless 
and  will  avoid  repetition  and  confusion. 

The  human  brain  is  composed  of  four  distinct  portions.1 
The  anterior  plane  includes  the  frontal  lobe  ;  the  middle 
plane  includes,  superiorly  the  parietal  lobe,  inferiorly  the 
sphenoidal,  the  posterior  plane  the  occipital  lobe.2 

To  these  we  will  add  other  lobes  of  secondary  importance, 
at  least  to  man  :  the  olfactive,  very  reduced  ;  the  gyrus 
hippocampi,  impossible  to  well  determine  ;  the  lobe  of  the 
Island  of  Reil,  deeply  hidden  in  the  depths  of  the  fissure  of 
Sylvius;  the  lobe  of  the  corpus  callosum,  and  the  gyrus 
angularis. 

In  the  lobes  are  to  be  distinguished  lobules  and  convolu- 
tions. The  lobules  are  but  topographic  regions,  whereas 
the  convolutions  have  a  real  anatomical  existence. 

Between  the  various  lobes  are  fissures. 

Between  the  frontal  and  parietal  lobes  is  the  fissure  of 
Rolando;  between  the  parietal  lobe  and  the  gyrus  angularis 
is  the  occipital  fissure  (or  perpendicular)  ;  between  the 
fronto-parietal  lobe  and  the  temporal,  is  the  fissure  of  Syl- 
vius. 

Between  the  fronto-parietal  lobe  and  the  lobe  of  the  cor- 
pus callosum  lies  the  calloso-marginal  fissure. 

Between  the  occipital  lobe  and  the  gyrus  angularis  lies 
the  fissure  calcarina. 

1  The  anatomy  and  morphology  of  the  convolutions  belong  entirely  to  French 
science  ;  Vicq  d'Azyr,  Rolando,  Foville,  Leuret,  Gratiolet,  Broca. 

2  We  adopt  the  terms  employed  by  Broca.  Mém.  sur  la  nomenclature  céré- 
brale (Revue  d'Anthrop.,  1878,  p.  193). 


48 


CEREBRAL   CONVOLUTIONS. 


Between  the  convolutions  are  furrows  (sulci). 

The  frontal  lobe  is  composed  of  three  convolutions  :  first 
or  superior,  second  or  middle,  and  third  or  inferior.1 

The  inferior  portion  of  the  frontal  lobe  is  known  as  the 
orbital  lobule  ;  upon  which  may  be  observed  three  orbital 
volutions,  prolongations  of  the  frontal  volutions. 

Surrounding  the  fissure  of  Rolando  are  two  important 
convolutions  ;  anteriorly  the  ascending  frontal  convolution 

Sup.  pariet'l  Jyobule. 

/ 

/ 

Rolando. 

^ -parietal  £ 

.-K fissure.    *« 
S    \  pu 


Fissure  of  $ylviu< 


Parallel  fissure. 


Fig.  7. — Convex  surface  of  a  hemisphere  of  the  human  brain  (parietal  lobe 
partly  schematic).     (Foville.) 

or  better,  pre-rolandic,  which  seems  to  give  three  prolonga- 
tions, that  is,  the  three  frontal  convolutions.  Posteriorly 
is  the  ascending  parietal,  or  better,  post-rolandic. 

The  union  of  these  two  convolutions  on  the  internal  face 
of  the  hemisphere  forms  the  paracentral  lobule. 

The  temporal  lobe  includes  the  first,  second,  and  third 
temporal  convolutions,  Fig.  7.     The  fissure  separating  the 


1  As  remarked  by  Charcot,  it  would  be  proper  to  make  an  exception  and  call 
the  third  frontal  convolution  the  convolution  of  Broca. 


PHYSIOLOGY    OF    THE    CONVOLUTIONS. 


49 


first  and  second  temporal  convolutions  is  the  parallel  fis- 
sure, which  terminates  in  the  parietal  region,  called  gyrus 
angularis. 

The  parietal  lobe  is  divided  into  two  parts  by  the  inter- 
parietal fissure.  This  gives  a  superior  and  an  inferior 
parietal  lobule. 

The  occipital  lobe  embraces  the  first,  second,  and  third 
occipital  convolutions.  Inferiorly,  the  temporal  and  occi- 
pital lobes  seem  confounded,  so  as  to  furnish  a  first  and 
second  temporo-occipital  convolution. 


-ssJ»^- — y -^    * 


Fiss.of  Rolande 

cent,,  conv. 
|Post.cent.ccav. 


Fig,  S. — Internal  face,  right  hemisphere  of  human  brain  (Ecker.) 

This  nomenclature  applies  equally  to  man  and  monkey  ; 
but  as  one  cannot  experiment  upon  man,1  and  as  physiolo- 
gists rarely  have  monkeys  at  command,  it  is  of  special  im- 


1  There  are  exceptions  to  all  rules.  Bartholow  (Revue  des  Scien.  Méd.,  t.  iv., 
1874,  p.  65),  gives  some  interesting  experiences  with  one  of  his  patients.  He 
plunged  needles  into  different  parts  of  the  brain,  passed  electric  currents 
through  them,  and  watched  the  results.  The  patient  died  two  days  after,  but 
lhe  needles  had  nothing  to  do  with  the  death! 


5o 


CEREBRAL   CONVOLUTIONS. 


portance  to  have  a  full  knowledge  of  the  dog's  brain  and 
its  comparative  parallelism  with  man's.  Thus  pathological 
facts  in  man  and  physiological  experiments  upon  the  dog 
can  be  systematically  compared,  so  that  a  very  good  idea 
can  be  obtained  of  the  functions  of  the  various  convolutions 
according  to  their  location. 

The  configuration  of  the  dog's  brain,  as  first  shown  by 
Gratiolet,  has  no  direct  relation  with  man's,  at  least  the 
homologies  are  not  at  first  seen,  and  the  type  is  different. 

The  fissure  of  Sylvius  exists,  but  not  that  of  Rolando  ; 
or  at  least  it  is  replaced  by  a  much  more  anterior  fissure, 
called  the  crucial  (B,  Fig.  9). 


Fig.  9. — Right  hemisphere  of  dog's  brain  (after  Ferrier). 

A,  Fissure  of  Sylvius  ;  B,  crucial  fissure  ;  O,  olfactive  bulb;  I.,  II.,  III.,  and 
IV.  represent  respectively  the  first,  second,  third,  and  fourth  convolutions. 


The  crucial  fissure  crosses  the  inter-hemispheric  fissure 
at  right  angles,  giving  the  appearance  of  a  cross.  It  is  the 
same  with  the  cat,  only  that  the  crucial  fissure  is  still  more 
anterior  than  in  the  dog. 

About  the  crucial  fissure  is  a  convolution  which  seems 
to  respond  to  the  pre-  and  post-rolandic  convolutions  in 
men. 

The  olfactive  lobe  is  greatly  developed,  the  frontal 
scarcely  at  all. 


HISTORICAL    INTRODUCTION.  5  I 


HISTORICAL  INTRODUCTION. 

The  brain  of  man  differing  greatly  from  that  of  animals, 
it  can  be  foreseen  that  experiments  upon  animals  will 
not  give  results  exactly  applicable  to  man.  This  fact  must 
be  specially  emphasized,  as  it  is  a  very  important  and  com- 
manding one. 

Compare  the  human  blood  with  that  of  the  sheep  or 
fish.  As  these  different  kinds  of  blood  have  the  same 
functions  (absorption  of  oxygen  and  nutrition  of  tissues), 
have  the  same  general  chemical  constitution  and  a  very 
analogous  anatomv,  it  will  suffice  to  examine  the  function 
of  the  sheep's  or  fish's  blood  in  order  to  understand  the 
function  of  human  blood. 

The  same  for  other  tissues  and  organs  ;  the  kidneys  for 
example,  or  the  muscular  tissue.  The  same  also  for  cer- 
tain nervous  functions,  innervation  of  the  heart  or  blood- 
vessels :  that  observed  in  animals  can  serve  in  human 
physiology. 

But  for  the  encephalon,  and  especially  for  the  cerebral 
convolutions,  this  identity  no  longer  holds. 

For  example,  if  Cuvier's  brain  be  compared  to  that  of  a 
dog,  it  will  be  seen  that  the  anatomical  constitution  and 
the  physiological  function  are  very  different  ;  and  there- 
fore the  conclusions  of  physiological  experiments  upon 
the  brain  of  a  dog  cannot  be  applied  exactly  and  abso- 
lutely to  the  human  brain. 

A  very  important  reserve,  however,  should  always  be 
made  ;  that  is,  that  these  differences  are  quantitative,  not 
qualitative.  To  explain  :  The  reaction  of  the  cortex  cere- 
bri to  excitants  should  be,  and  really  is,  identical  in  man 
and  dog;  it  would  be  more  or  less  marked,  more  or  less 
extensive  in  one  case  or  the  other  ;  but  the  functional 
essence  would  remain  identical,  as  is  the  case  with  the 
blood,  the  spinal  cord,  the  nerves,  and  heart. 


52  CEREBRAL   CONVOLUTIONS. 

If  we  observe  that  the  cortex  cerebri  is  both  motor  and 
sensorial  in  the  dog,  that  would  be  sufficient  to  allow  us 
to  affirm  the  same  in  case  of  man. 

The  question  can  be  stated  still  more  clearly.  In  the 
sigmoid  gyrus  of  the  dog,  we  find  a  motor-centre  for  the 
fore-legs  ;  that  permits  us  to  say  that  it  also  exists  in  man. 
But  can  we  venture  to  say  that  this  motor-centre  in  man 
is  near  the  fissure  of  Rolando,  and  that  the  ascending 
frontal  convolution  corresponds  to  the  sigmoid  gyrus  of 
the  dog  ?  Should  we  dare  to  say  that  there  exists  for 
the  anterior  member  one  motor-centre  and  not  two,  or 
three  or  four?  That  would  exceed  the  limits  of  legitimate 
deduction.  From  the  fact  that  there  are  motor-centres  in 
the  dog,  we  may  conclude  that  there  are  also  motor-centres 
in  man.  From  the  fact  that  intelligence  in  the  dog  de- 
pends upon  the  convolutions,  we  may  conclude  that  it  is 
the  same  with  man  ;  but  we  can  go  no  further. 

Applications  to  human  physiology  would  very  soon  be 
limited  were  there  not  another  precious  source  of  knowl- 
edge ;  that  is,  pathological  anatomy  and  physiology. 

Pathology  and  physiology  do  not  antagonize  ;  they  are 
two  branches  of  the  same  science,  biology,  and  they  should 
afford  mutual  light.  Though  physicians  are  too  often 
ungrateful  to  physiologists,  the  latter  should  not  return 
ingratitude,  and  disdain  the  countless  contributions  which 
are  scattered  through  medical  lore  upon  the  subject  of 
the  functions  of  the  cerebral  convolutions.  Good  obser- 
vations equal  good  experiments,  and  we  are  resolved  to 
profit  largely  from  the  valuable  gifts  which  pathological 
anatomy  offers  to  the  study  of  the  cortex  cerebri. 

However,  in  the  study  of  cerebral  convolutions,  the  two 
sciences  differ  in  their  points  of  advantage  and  disadvan- 
tage.    Physiology  has  these  two  advantages  : 

i  st.  The  experiment  can  be  repeated  as  often  as  desired. 

2d.  The  conditions  of  the  experiment  can  be  determined, 
a  thing  necessary  to  the  value  of  the  phenomenon. 

The  advantages  of  pathology  are  also  considerable. 


HISTORICAL   INTRODUCTION.  53 

ist.  The  lesions  are  upon  the  human  subject,  in  whom 
the  encephalon  differs  much  from  that  of  animals. 

2d.  The  lesions  are  always  better  limited  than  in  physio- 
logical experiments. 

3d.  The  symptoms  are  studied  for  a  much  longer  time, 
(and  probably  with  more  care). 

4th.  The  subject  can  describe  his  sensations. 

Thus  we  think  that  physiologists  should  profit  from  the 
results  of  pathology,  and  that  in  all  physiological  study 
we  should  highly  estimate  medical  observations  made  upon 
man. 

The  ancient  authors,  especially  Galen,1  had  very  incom- 
plete ideas.  Galen  called  the  gray  cortex  of  the  brain 
epencranis  {ènkynpavii),  after  Erasistratus,  and  the  folds 
of  the  brain  (eXixsc).  Erasistratus  thought  the  human 
epicranium  more  complex  than  animals,  for  the  reason 
that  he  has  more  intelligence.  To  this,  Galen  offered  a 
rather  worthless  argument:  "  Asses,"  he  said,  "  have  a  very 
complicated  encephalon,  whereas  their  imbecile  character 
would  exact  an  encephalon  quite  simple  and  free  from  varia- 
tions." Whatever  the  ground  of  that  strange  idea  respect- 
ing the  imbecility  of  the  ass  and  the  complexity  of  his 
convolutions,  it  may  be  seen  that,  even  in  ancient  times,  the 
brain  and  even  the  cortex  cerebri  was  considered  as  the 
seat  of  intelligence.  To  the  quotation  already  given  Galen 
added  this  curious  sentence,  showing  the  admirable  sa- 
gacity and  prudence  of  this  genius  : 

"  To  refrain  from  speaking  of  the  substance  of  the  soul, 
when  speaking  of  thcstructure  of  the  body  which  contains 
it,  is  impossible  ;  but  if  this  is  impossible,  it  is  possible  to 
turn  promptly  away  from  a  subject  upon  which  we  should 
not  dwell."  This  is  the  programme  which  we  shall  attempt 
to  follow. 

Galen  also  noticed   that  the  brain  is  insensible.'2     This 


1  De  usu  partium,  viii.,  13  Ed.  de  Daremberg,  t.  i.,  p.  563. 
i  Cité  par  Longet,  loc.  cit.,  p.  640. 

5 


54  CEREBRAL   CONVOLUTIONS. 

important  fact  has  since  been  observed  by  other  writers, 
and  seems  now  well  attested. 

From  Galen  to  the  commencement  of  the  present  cen- 
tury, only  scattered  facts  can  be  produced. 

Surgeons  of  the  seventeenth  and  eighteenth  centuries 
thought  that  lesions  of  the  cortex  cerebri  might  produce 
paralyses,  and  to  remedy  this,  they  had  recourse  to  trephin- 
ing ;  but  their  opinions  are  very  confused.  Concussion, 
and  above  all  compression,  played  the  principal  part  in 
their  theories.  It  should  be  remarked  also  that,  in  the 
cases  observed,  it  is  rare  that  the  lesions  are  exactly  lo- 
cated. Concussion,  consecutive  hemorrhage,  and  encepha- 
litis quickly  extended  to  all  parts  of  a  hemisphere. 

Lorry,1  however,  gave  some  very  exact  experiences  and 
stated  that  the  cerebral  pulp  was  insensible. 

Haller,2  with  some  important  restrictions,  expresses  very 
nearly  the  same  opinion.  He  says  that  it  is  necessary  to 
go  deeper  than  the  cortex  cerebri  in  order  to  provoke 
movements  or  sensations,  and  that  the  medulla  of  the  brain 
is  the  sensitive  portion. 

"  Non  ergo  videtur  aut  sensum  in  cortice  cerebri  exerceri,  nut 
plenam  perfectamque  causant  motus  musculosi  in  co  Jiabitare, 
cum  prœterea  plurima  expérimenta  demonstrent,  prof  undo  de- 
mum  loco,  et  a  cortice  cerebri  valde  remoto  mcdullam  lœdi  opor- 
tere,  ut  convulsio  superveniat."* 

I  dwell  upon  the  ancient  ideas  only  because  they  have 
not  until  the  present  ever  been  disturbed,  the  doctrine  of 
Galen,  Lorry,  and  Haller  having  held  sway  until  1870. 

The  importance  of  cerebral  convolutions  as  related  to 
the  intellectual  faculties,  though  suspected  by  physiologists 
and  medical  practitioners,4  was  especially  brought  to  light 
by  Gall.     Gall's  merit  was  not  the  invention  of  an  absurd 

1  Mém.  de  l'Acad.  des  Sciences  (Recueil  des  savants  étrangers,   1700,  t.  iii., 

P-  352). 

-  Elementa  physiologise,  t.  x.,  p.  312  et  suiv.,  lib.  x.,  §  xx.  Num  cerebri 
medulla  sentiat. 

3  Same,  p.  392,  §  xxiii. 

4  Van  Swieten,  t.  iii.,  p.  264  ;  t.  ii.,  p.  604,  Boerhave,  etc. 


HISTORICAL   INTRODUCTION.  55 

theory,  but  the  proving,  by  comparative  anatomy,  and  by 
the  study  of  the  brains  of  idiots  and  the  insane,  that  intelli- 
gence is  a  function  of  the  convolutions. 

He  was  followed  in  this  direction  by  Flourens,  one  of 
the  most  vigorous  opponents  of  phrenology.  This  cele- 
brated physiologist1  demonstrated  beyond  dispute  that 
the  encephalic  nervous  system  is  the  seat  of  intelligence, 
the  origin  of  sensation  and  motion.  From  this  time,  that 
which  was  previously  but  a  supposition  or  a  feeling,  be- 
came a  positive  acquisition  to  science,  based  upon  firm, 
unshakable  proofs. 

We  must  turn  to  the  experiences  of  contemporaneous 
physiologists  for  new  facts  respecting  the  physiology  of 
the  convolutions  ;  but  from  Flourens  to  the  present  time 
(evidently  guided  by  his  labors),  other  authors,  zoologists, 
and  medical  practitioners  have  furnished  a  large  number  of 
interesting  facts  well  calculated  to  illuminate  physiology. 

It  is  somewhat  remarkable  that  the  three  most  important 
observations  occurred  in  the  same  period,  and  are  due  to 
three  French  savants. 

1  st.  Desmoulins'2  demonstrated  by  comparative  anatomy 
that  the  number  and  perfection  of  the  intellectual  faculties 
are  in  direct  ratio  to  the  number  and  depth  of  the  cerebral 
convolutions. 

2d.  Calmeil,3  in  an  admirable  series  of  observations, 
proves  that  with  the  insane,  especially  with  general  paraly- 
tics, the  alterations  are  in  the  gray  portions  of  the  convo- 
lutions, and  that  therefore  there  is  a  direct  connection 
between  mental  disturbances  and  lesions  of  the  cortex 
cerebri. 

3.  Bouillaud,  the  illustrious  dean  of  French  medicine,' 
demonstrated  by  a  great  number  of  pathological  facts  that 
language  is  located  in  the  anterior  lobes  of  the  brain. 


1  Mémoires  lus  a  l'Institut,   1822,  1823.     Recherches  expérimentales  sur  les 
propriétés  et  les  fonctions  du  système  nerveux,  1st  Ed.  1824,  2d  Ed.  1842. 
"Anatomie  du  système  nerveux  des  vertébrés,  2d  partie,  p.  606,   Paris,  1825. 

3  De  la  paralysie  chez  les  aliénés,  Paris,  1826. 

4  Traité  de  l'encéphalite,  Paris,  1825,  p.  279. 


56  CEREBRAL   CONVOLUTIONS. 

From  1825  to  1861,  the  physiological  history  of  the  cor- 
tical system  remained  absolutely  stationary.  In  1861, 
Paul  Broca,  in  a  remarkable  mémoire1  made  it  apparent 
that  language  was  not  only  located  in  the  anterior  lobe, 
but  that  it  was  confined  to  a  special  convolution,  and  to 
the  posterior  portion  of  that  convolution  (third  convolu- 
tion of  left  frontal  lobe).2 

About  this  time,  the  conformation  of  the  human  brain 
began  to  be  looked  upon  as  an  orderly  development 
instead  of  a  result  of  chance.  The  researches  of  Foville, 
and  those  of  Leuret,  Gratiolet,  and  Broca  (1 855—1865),  es- 
tablished the  constancy  of  the  form  of  the  convolutions. 

Excepting  some  isolated  instances,  the  profession  did  not 
admit  the  localization  of  cerebral  functions,  beyond  that 
concerning  language.3 

The  celebrated  researches  of  Fritsch  and  Hitzig4  ter- 
minated these  hesitations  and  established  the  motor-power 
of  the  cortex  cerebri. 

Whatever  interest  attaches  to  subsequent  labors,  it  must 
be  recognized  that  the  first  work  of  Fritsch  and  Hitzig 
contains  all  that  is  essential  upon  the  question.5  They  have 
shown  : 

1  st.  That  there  are  motor-centres  in  the  brain  (excitable 
by  electricity),  and  again  that  certain  portions  are  not  thus 
excitable  (p.  311). 

2d.  That   the    points    where    excitation   affects    certain 


1  Sur  la  siège  de  la  faculté  du  langage  articulé,  avec  deux  observations 
d'aphémie.      Bull,  de  la  soc.  anat.,  2d  série,  t.  iv.,  1861. 

'2  It  is  but  just  to  say  that  the  relation  between  language  and  a  lesion  of  the 
left  hemisphere  had  been  noted  by  Dax  in  1836  (See  Dax  fils,  Gaz.  hebd.,  28th 
April,  1865. 

3  Hughlings  Jackson,  1868. — Prévost,  a  pupil  of  Vulpian,  says  in  his  inau- 
gural thesis,  p.  140,  "  crossing  of  the  eyes  may  be  observed  in  cases  of  super- 
ficial lesions  of  a  hemisphere."      1868. 

4  Ueber  die  Electrische  Erregbarkeit  des  Grosshirns.  Arch,  fur  Anat.,  1870, 
28th  April,  p.  300-332. 

5  It  may  be  interesting  to  read  the  polemic  acerbity  of  Hitzig  respecting 
Carville  and  Duret.  Gaz.  méd.,  1875,  Feb.  6th,  and  Arch,  fur  Anat.,  etc.- 
1875,  p.  428  et  suiv.     But  Hitzig  defends  a  cause  not  attacked. 


HISTORICAL   INTRODUCTION.  57 

groups  of  muscles  are  very  precisely  limited  to  a  small  area 
of  the  cerebral  surface  (p.  311). 

3d.  That  the  results  are  more  regular  with  the  direct 
than  with  the  induced  current  (p.  316). 

4th.  That  the  removal  of  a  localized  cerebral  region  with 
the  scalpel  will  produce  paralyses  (p.  328). '  The  question 
of  motor  functions  of  the  convolutions  has  been  considered 
by  numerous  writers.  Among  all  the  newly  demonstrated 
facts  there  are  four  of  some  importance  : 

A.  There  are  no  motor-centres  in  the  newborn  (Solt- 
mann). 

B.  Excitation  of  the  white  layer  below,  gives  the  same 
results  as  exciting  the  gray  substance  above  (Dupuy,  Car- 
ville,  and  Duret). 

C.  The  motor-centres  of  the  limbs  are  also  vaso-motor 
excito-secretor  (Boc  he  font  aine  and  Lépine),  and  sensorial  cen- 
tres (Vulpian). 

D.  There  are  sensorial  centres  in  the  occipital  convolu- 
tions (Ferrier). 

In  a  medical  point  of  view,  the  researches  of  Charcot 
and  his  pupils  have  established  upon  a  firm  basis  the  theory 
of  localization,  thus  medicine  has  lent  to  physiology  a  proof 
which  was  perhaps  necessary  before  admitting  the  exist- 
ence of  motor-centres. 

We  will  now  study  the  physiology  of  the  convolutions 
under  two  aspects  ;  the  properties  of  the  gray  cortex,  and 
its  functions.     Indeed,  in  the  physiology  of  organs  there 


1  Some  remarks,  more  or  less  precise,  do  not  establish  the  title  of  priority  to 
a  discovery.  A  single  observation  of  Griesinger  (see  Bernhardt,  Arch,  fur 
Psychiatrie,  iv.,  p.  480),  or  a  remark  of  Eckert  (Exper.  Phys.  des  Nervensystems 
Giessen,  1867,  p.  157)  are  not  sufficient.  In  this  way  Breca  should  be  cited 
who  says,  in  1861  (Bull,  de  la  Soc.  d'anthropol.,  p.  318)  :  "  The  posterior  con- 
volutions differ  notably  from  the  middle  and  anterior  convolutions.  The  prin- 
ciple of  cerebral  localizations  is  established  both  by  physiology  and  pathology, 
the  latter  showing  the  independence  of  the  functions,  and  also  by  anatomy, 
■which  shows  the  diversity  of  the  organs."  Neither  should  the  persevering  labors 
of  H  ughlings  Jackson  be  forgotten.  But  these  do  not  take  from  Fritsch  and 
Hitzig  the  incontestable  right  of  priority. 


58  CEREBRAL   CONVOLUTIONS. 

should  always  be  distinguished  a  state  of  repose  and  one  of 
activity  ;  they  may  be  termed,  respectively,  static  and 
dynamic. 

According  to  this  division,  we  will  first  examine  the  ex- 
citability of  the  convolutions,  their  electric  condition,  and 
their  nutrition.  In  the  second  chapter,  we  will  consider 
their  relations  and  functions  in  the  organism  as  regards 
motion,  sensation,  and  intelligence. 


PHYSIOLOGICAL   PROPERTIES    OF   THE   CONVOLUTIONS.    59 


FIRST   CHAPTER. 

PHYSIOLOGICAL    PROPERTIES   OF   THE    CON- 
VOLUTIONS. 

A. — EXCITABILITY. 

The  apparent  inexcitability  of  the  cerebral  surface,  the 
inability  of  chemical,  mechanical,  or  other  agents  to  pro- 
voke motion  is  something  which  has  attracted  the  attention 
of  all  observers  from  Galen  to  Lorry.  The  experiment  of 
Fritsch  and  Hitzig,  however,  renewed  attention  to  the  sub. 
ject,  and  to-day  the  question  stands,  Is  the  gray  substance 
inexcitable  ? 

Writers  generally  hold  that  mechanical  and  chemical 
agents  are  incapable  of  exciting  motion.1 

Respecting  the  chemical  or  mechanical  inexcitability  of 
the  gray  substance,  however,  authors  are  not  in  accord. 
Brown-Séquard2  has  recently  made  some  interesting  experi- 
ments in  this  field.  According  to  him,  mechanical  and 
especially  thermic  excitations  of  the  cerebral  surface  pro- 
duce, at  least  temporarily,  the  same  effects  as  a  section  of 
the  cervical  sympathetic  nerve  of  the  side  corresponding 
to  the  excitation.  These  phenomena  would  be  as  complete 
as  after  section  of  the  sympathetic  ;  moreover,  that  action 
would  not  be  produced  except  after  excitation  of  the  right 
hemisphere.  Eulenberg  and  Landois  have  noticed  analo- 
gous phenomena.  In  applying  sea-salt  to  the  cerebral  sur- 
face, they  found,  first,  a  lowering  of  temperature  (excitation) 
followed  by  an  elevation  of  temperature  in  the  fore-limbs, 


1  Nothnagel,  cited  by  Dupuy  (Lond.  Times  and  Gazette,  No.  1410,  1877), 
found  the  rabbit's  brain  mechanically  excitable  with  a  needle.  Dupuy  wittily 
added  that  Nothnagel's  rabbits  differed  from  those  which  could  be  obtained  in 
France  and  England  (see  Nothnagel,  Virchow's  Arch.,  lviii.,  p.  420). 

2  Arch,  de  physiol.,  1875,  P-  854. 


6o  CEREBRAL   CONVOLUTIONS. 

which  they  attributed  to  the  destruction  of  the  gray  cor- 
tex.1 

We  cannot  tell  how  far  these  effects  are  attributable  to 
the  action  of  the  cerebral  cortex.  It  is  likewise  doubtful 
if  movements  of  the  limbs,  such  as  those  following  galvanic 
excitation,  can  be  produced  by  mechanical  or  chemical 
excitations  to  the  brain,  or  if  either  the  gray  or  white  cere- 
bral substance  can  be  excited  by  those  agents. 

The  question  of  excitation  by  galvanism  is  still  more 
difficult  and  more  undecided. 

When  certain  regions  of  the  gray  cortex  are  excited,  the 
sigmoid  gyrus  in  the  dog  for  example,  either  by  a  moderate 
direct,  or  an  induced  electrical  current,  movements  of  the 
limbs  follow,  and  it  may  be  concluded  that  the  gray  sub- 
stance has  been  excited  and  has  produced  them. 

The  conclusion,  however,  would  be  rather  superficial, 
and  we  are  indebted  to  Dupuy  2  and  Carville  and  Duret 3 
for  having  shown  that  the  electric  current  diffuses  at  the 
base  of  the  brain,  and  produces  excitement  of  the  white 
substance. 

In  placing  at  the  base  of  the  brain  the  nerve  of  a  galva- 
noscopic  frog,  Dupuy  has  seen  electrization  of  the  sigmoid 
gyrus  produced  a  movement  of  the  paws  as  before  men- 
tioned. 

Carville  and  Duret  have  also  studied,  with  the  galvano- 
meter, electric  diffusion  upon  the  brains  of  both  dead  and 
living  animals,  and  they  have  noticed  very  feeble  induced 
currents  to  extend  themselves  from  one  to  another  point  of 
the  periphery,  extending  at  the  same  time  also  a  certain 
distance  down  into  the  white  substance. 

It  always  seemed  to  me  that  experiments  with  the  gal- 
vanometer were  of  no  special  importance,  and  proved  very 


1  Berl.   Klin.  Woch.,  1876,    Nos.  42  and  43,  also  Virchow's  Arch.,  t.  lxviii., 

P-  245. 

-  Thèse   inaugurale,  Paris,  1873.     Examen   de  quelques   points  de  la  physi- 
ologie du  cerveau,  pp.  23,  26. 

3  Bull,  de  la  Soc.  de  Biol.,  20th  Dec,  1874,  p.  374. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.   6 1 

little,  for  the  reason  that  the  instrument  is  so  sensitive  that 
it  shows  currents  of  diffusion  almost  everywhere.  In 
electrizing  the  right  arm,  there  will  be  produced  an  electric 
state  of  the  left  arm,  and  a  current  which  will  produce  an 
enormous  deviation  of  the  galvanometer.1 

It  is  preferable  to  use  the  sciatic  of  the  frog,  which  has 
a  very  sensitive  reaction,  and  evidently  quite  sufficient,  for 
when  the  nerve  will  not  react,  the  cerebral  substance  can- 
not, as  it  is  less  easily  excited  than  the  galvanoscopic  leg. 

Very  moderate  electric  currents  induce  movements  in 
the  legs  of  a  dog  ;  but  the  galvanoscopic  leg  will  not  be 
excited,  provided  it  is  placed  at  a  sufficient  distance  from 
the  cerebral  points  excited,  say  one  or  two  centimetres  or 
more  ;  consequently,  the  electric  current,  though  diffused 
physically,  is  not  physiologically  so  diffused  but  that  the 
excitation  may  be  limited  to  certain  well-defined  portions 
of  the  brain. 

Moreover,  a  very  simple  experiment  demonstrates  that 
the  current  may  be  localized  in  certain  points  of  the  peri- 
phery, since  either  negative  or  positive  effects  can  be 
obtained  at  will  by  exciting  two  points  separated  by  inter- 
vals of  not  more  than  one  or  two  millimetres  2  (Rouget). 

I  have  made  analogous  experiments  with  the  galvanic 
limb  and  with  well-defined  results.  To  excite  the  sciatic 
nerve  it  was  only  necessary  to  bring  it  near  the  electrodes. 
But  if  the  electrodes  were  close  together,  and  the  current 
not  too  strong,  there  would  be  at  one  or  two  centimetres 
distance  from  them  no  diffusion. 

It  is  not  simply  a,  question  of  peripheric  diffusion,  for 
the  diffusion  from  the  periphery  to  the  parts  underneath 
cannot  be  avoided.  The  gray  layer  is  so  thin  that  it  can- 
not be  expected  to  limit  excitation  to  that  part  alone,  so 
that  the  current  necessarily  extends  to  and  excites  the 
subjacent  white  layers. 

1  Onimus  :  Bull,  de  la  Soc.  de  Biol.,  1867  and  1874,  p.  379. 
9  Cited  by  Bochefontaine,  Arch,  de  Phys.,  1876,  p.  171,  et  Bull,  de  la  Soc.  de 
Biol.,  1875,  p.  131. 


62  CEREBRAL   CONVOLUTIONS. 

This  suggested  another  experiment.1  In  place  of  excit- 
ing the  gray  substance,  that  can  be  removed,  and  the  white 
substance  underneath  excited. 

Many  writers  have  made  experiments,  but  without  ac- 
cord in  results. 

Putnam,2  on  the  one  hand,  has  observed  that  in  removing 
a  bit  of  the  gray  cortex  and  exciting  the  subjacent  white 
substance  a  stronger  excitant  was  required  to  produce  a 
movement.  In  replacing  the  bit  which  had  been  cut  out, 
the  currents  were  without  effect  ;  he  therefore  concludes 
that  the  gray  substance  itself  is  susceptible  of  excitation. 

Carville  and  Duret  had  a  similar  experience  respecting 
the  necessity  of  a  stronger  current,  where  the  gray  sub- 
stance had  been  removed. 

Hermann3  and  Braun,4  on  the  other  hand,  have  obtained 
quite  different  results.  Hermann  shows  that,  after  de- 
stroying the  gray  substance  with  chemical  cauteries,  a  very 
feeble  current  sufficed  to  produce  movements,  and  that  in 
cutting  away  slices  from  the  brain  the  effect  was  decided 
in  proportion  as  the  central  regions  were  approached.  In 
some  cases,  however,  it  was  necessary  to  increase,  in 
others  to  diminish  the  force  of  the  current 

To  this,  Braun  has  added  the  important  fact,  that  if 
the  white  fibres  beneath  the  point  excited  be  cut,  the  exci- 
tation fails  to  produce  the  movement  which  occurred  be- 
fore the  section  of  the  white  fibres.  The  section  does  not 
prevent  the  receiving  of  currents,  though  in  exciting  the 
surface  the  corpora  striata  are  not  excited,  but  only  the 
subjacent  white  substance    or   the  gray  substance  itself. 

1  Upon  this  subject  see  Vulpian's  lesson,  June  29th,  1876  ;  in  Journal  l'Ecole 
de  medicine  ;  Carville  and  Duret,  Arch,  de  Phys.,  1875  ;  Bourdon-Sanderson, 
Proceed.  Roy.  Soc,  June,  1874,  xxii.,  p.  338  ;  Furrier,  Functions  of  the  Brain, 
p.  218. 

2  Boston  Med.  and  Surg.  Journal,  July,  1874. 

3  Ueber  elektrische  Reizversuche  an  der  Grosshirnrinde,  Pfluger's  Archiv.,  t. 
x.,  p.  77- 

4  Eckhard's  Beitrâge,  etc.,  1874,  t.  vii.,  p.  127.  Beitrâge  zur  Frage  iiber  die 
elektrische  Erregbarkeit  des  Grosshirns. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.   63 

When  the  gray  substance  which  has  been  removed  from 
above  the  white  is  replaced  and  electrized,  it  will  be  ob- 
served to  have  become  inert,  resulting  from  the  section. 

Other  well-attested  facts  prove  also  that  in  exciting  the 
cerebral  periphery  the  corpora  striata  are  not  affected. 
Carville  and  Duret  observed,  in  experimenting  with  a  dog, 
that  very  strong  electric  currents  would  produce  no  mus- 
cular movements  ;  autopsy  brought  to  light  a  considerable 
lesion  of  the  centrum  ovale,  thus  interrupting  the  physio- 
logical, though  not  the  physical  continuity  between  the 
corpora  striata  and  cortex  cerebri.  The  corpora  striata 
were  sound.  The  excitation  then  was  not  diffused  beyond 
the  border  of  the  corpus  striatum.1  Ferrier  remarks  that 
excitation  of  the  corpora  striata,  or  of  the  peduncles,  gives 
quite  different  results  from  excitation  of  the  cortex  cerebri.2 

Franck  and  Pitres,  in  the  remarkable  researches  which 
they  have  undertaken  upon  the  functions  of  the  cerebral 
hemispheres,  have  often  noticed  that  electrization  of  the 
corpora  striata,  carefully  avoiding  the  white  fibres  which 
penetrate  the  nuclei  of  the  gray  substance,  is  absolutely 
without  results.3 

The  general  conclusion  then  is  :  in  exciting  the  cortex 
cerebri,  there  are  currents  of  diffusion  to  the  periphery 
and  towards  the  centre  ;  but  these  currents  are  insufficient 
to  excite  either  the  entire  periphery  or  the  subjacent  cen- 
tral ganglia. 

Respecting  the  greater  or  less  degree  of  excitability  of 
the  white  substance,  when  the  gray  substance  is  avoided 
or  destroyed,  there  are  great  differences  of  opinion.  Tn 
closely  examining  the  facts,  however,  that  discord  is  found 
to  result  from  a  difference  of  conditions. 

1  Carville  and  Duret  :  Notice  of  a  pathological  Lesion  of  the  Centrum  Ovale 
in  a  Dog.     Arch,  de  physiol.,  1875,  p.  136. 

2  Functions  of  the  Brain,  French  trans.,  1875,  p.  258  et  suiv. 

3  A  portion  of  the  researches  of  Franck  and  Pitres  has  been  communicated 
to  the  Soc.  de  Bi  >1.,  Nov.  and  Dec,  1877.  See  Gaz.  méd.  of  Jan.  3d,  1877. 
But  many  of  the  facts  here  given  are  unpublished,  and  we  are  indebted  for 
them  to  our  good  friend,  Fr.  Franck. 


64  CEREBRAL   CONVOLUTIONS. 

In  one  of  the  experiments  which  I  made  with  Bochefon- 
taine,  in  the  laboratory  of  Vulpian,the  following  facts  were 
observed  : 

A  dog  was  chloralized  and  the  sigmoid  gyrus  exposed. 
In  exciting  the  anterior  part  by  a  current  of  variable  inten- 
sity, it  was  found  that  in  order  to  provoke  a  movement  it 
required  an  electric  current  (induced,  continuous)  corre- 
ponding  in  strength  to  No.  12  upon  the  indicator  of  Du- 
bois-Reymond.1 

After  cutting  away  the  gray  substance  and  exciting  the 
white  substance  immediately  underneath  (before  the  occur- 
rence of  congestion  caused  by  the  cut),  a  very  feeble  cur- 
rent, scarcely  sensible  to  the  tongue — 23,  sufficed  to  provoke 
motion. 

After  the  lapse  of  an  hour,  excitability  had  greatly  dim- 
inished, 1 1  being  required  to  produce  motion,  and  the  exci- 
tability rapidly  vanished. 

This  was  followed  by  exposing  the  right  hemisphere  to 
12,  the  gray  substance  did  not  respond  to  the  excitation, 
though  upon  removing  the  gray  substance,  the  white  sub- 
stance responded  to  12. 

This  would  allow  the  conclusion  that  the  white  substance 
is  more  excitable  than  the  gray. 

Still,  as  Franck  has,  in  a  large  number  of  experiments, 
uniformly  obtained  a  great  diminution  of  excitability  after 
removal  of  the  gray  cortex,  and  as  my  experiment  just 
given  is  very  clear,  I  see  no  possible  explanation  of  the  dis- 
agreement except  in  the  difference  of  experimental  condi- 
tions. The  dogs  upon  which  I  experimented  were  chlor- 
alized, whilst  Franck's  were  neither  anaesthetized  nor  under 
influence  of  curare.  It  seemed  as  though  the  chloral  had 
paralyzed  the  gray  cortex,  thus  interposing  an  inert  tissue 
between  the  electric  excitation  and  the  white  fibres  which 
alone  were  susceptible. 

1  That  index,  though  very  imperfect,  is  perhaps  all  that  is  necessary  for  phy- 
siological uses.  With  an  ordinary  Gremet  pile,  o  indicates  very  strong,  10 
middling,  20  very  feeble,  30  perceptible  only  to  the  galvanometer. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.   65 

These  various  experiments  seem  to  prove  that  it  is  the 
gray  substance  which  is  really  excited. 

To  these  facts  are  associated  other  phenomena  espe- 
cially pertaining-  to  the  cortex  cerebri  ;  they  show  that  its 
reaction  to  excitation  differs  from  the  reaction  of  nerve- 
trunks.  As  I  have  had  occasion  to  demonstrate  elsewhere,1 
it  appears  that  successive  excitations  do  not  accumulate 
in  the  nerve,  whereas  it  is  quite  probable  that  they  do  in 
the  receiving  organs,  whether  muscular  or  sentient. 

It  was  of  interest  to  ascertain  if  the  cortex  cerebri  acted 
in  the  same  manner,  and  here  is  the  result  of  experiment. 

With  a  chloralized  dog,  excitation  of  the  antero-superior 
portion  of  the  sigmoid  gyrus  induced  movements  of  the 
eyelids  upon  the  same  side  and  of  the  fore-legs  of  the  oppo- 
site side.  Currents  were  frequently  repeated  at  a  strength 
of  10,  Dubois-Reymond  indicator. 

At  o°  (maximum)  with  a  single  excitation  (closed  or  open) 
there  followed  no  effect. 

A  movement  could  be  induced  by  making  with  the  hand 
three  or  four  tolerably  rapid  interruptions.  In  replacing 
the  indicator  at  io°,  very  frequent  excitations  produced 
movements  both  of  eyelids  and  fore-legs,  but,  as  has  been 
noticed  by  Schiff,  the  movements  were  very  retarded. 

That  retardation  only  signifies  that  the  excitations  are 
accumulated,  and  that  they  end  in  producing  a  result  :  the 
first  excitations  give  no  result,  the  last  only  (which  includes 
the  previous  ones)  does. 

To  explain  this  phenomenon  it  will  perhaps  be  well  to 
introduce  one  of  my  old  tracings.  It  shows  that  frequently 
repeated  excitation's  end  by  accumulation  and  produce  no 
motion  except  when  made  with  a  certain  frequency  (fig.  10). 

I  have  obtained  phenomena  which  can  be  compared,  by 
exciting  the  cerebral  surface  of  a  dog,  and  registering  his 
movements. 

After  adapting  an  instrument  to  register  the  muscular 

1  Thèse  inaug. ,  Recherches  sur  la  sensibilité.     Paris,  1877. 


66 


CEREBRAL   CONVOLUTIONS. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.   6j 

movements  of  the  fore-legs,  1  observed  that  isolated  exci- 
tations produced  no  effect,  whereas  closely  succeeding 
excitations  produced  a  manifest  tetanus  (fig.  n). 

In  a  similar  experiment,  MM.  Franck  and  Pitres  have 
also  observed  this  addition  of  excitation,  even  when  they 
were  somewhat  separated  (fig.  12). 

It  cannot  be  supposed  that  we  are  here  dealing  with 
latent  accumulations  either  in  the  gray  ganglionic  sub- 
stance or  in  the  subjacent  white  fasciculi  ;  in  fact,  direct 
excitation  of  these  fasciculi,  after  removal  of  the  gray  cor- 
tex, gives  no  accumulation  of  excitations. 


Fig.  12. — Addition  of  excitations  in  the  substance  of  the  gray  cortex.  From 
a  to  b,  excitations  induced  without  effect.  The  line  commences  to  wave  at  b, 
and  continues  to  increase.  At  the  bottom,  line  of  vibrations  of  the  diapason. 
(One  hundred  vibrations  per  second.) 

As  a  result  of  all  these  facts  it  seems  that  the  gray  cortex 
is  directly  excitable. 

A  number  of  other  experiments  also  support  this  hypo- 
thesis. Pitres  and  Franck  have  shown  that  the  interposi- 
tion of  the  gray  substance  produces  a  retardation  of  -^ 
in  a  second,  a  small  figure  of  itself,  but  enormous  consider- 
ing the  trifling  distance  of  only  some  millimetres.  This 
indicates  that  the  subjacent  white  fasciculi  are  not  excited, 
but  rather  the  gray  cortex,  which  responds  very  slowly 
to  the  excitation. 

It  has  been  objected  that  abrasion  of  the  gray  cortex 
does  not  prevent  the  action  of  electricity,  the  subjacent 
white  fasciculi  alone  being  excited.     But  does  that  prove 


68  CEREBRAL   CONVOLUTIONS. 

that  the  cortex  is  not  a  centre  ?  Not  at  all.  Let  us  sup- 
pose, as  Vulpian  has  said,  that  the  abraded  cortex  is  really 
a  centre,  it  must  have  conductors  which  run  to  the  deep 
part  of  the  brain.  These  conductors  are  precisely  the 
white  fibres,  and  excitation  of  the  conductors  should  give 
the  same  results  as  excitation  of  the  centres  from  whence 
they  start. 

The  reason  adduced  by  Dupuy,  that  there  were  no  centres 
in  the  cortex  because  chemical  or  mechanical  excitation 
produced  no  reaction,  is  evidently  insufficient  ;  indeed,  the 
white  substance  which  does  not  respond  to  chemical  exci- 
tants evidently  does  respond  to  electricity  ;  so  that,  should 
any  part  of  the  nervous  system  may  respond  to  chemical 
agents,  that  would  be  no  proof  that  it  would  not  respond 
to  electricity. 

We  cannot  dwell  upon  these  facts,  and  will  but  add  a 
resume  : 

i st.  Peripheric  diffusion  can  be  avoided,  but  diffusion 
from  the  gray  to  the  white  substance  cannot  be  avoided. 

2d.  The  white  substance  of  the  brain  is  certainly  excita- 
ble, as  Haller  thought,  and  contrary  to  Flourens'  opinion. 

3d.  The  cortex  cerebri  is  probably  excitable  by  elec- 
tricity, though  it  is  nearly  impossible  to  furnish  direct 
proof  of  it. 

4th.  In  the  order  of  electric  excitability  of  the  nervous 
system,  there  may  be  admitted  (though  perhaps  as  yet  some- 
what hypothetically)  :  (a),  the  nerve  terminations  ;  (b),  nerve- 
trunks  ;  (V),  central  gray  substance;  (d),  white  substance  of 
the  nerve-centres. 

I  will  also  call  attention  to  an  important  fact  hitherto 
imperfectly  studied  ;  that  is,  the  rapidity  with  which  exci- 
tation disappears.  It  seems  that  the  nervous  centres  are 
much  more  delicate  than  the  nerve-trunks,  and  that  ex- 
haustion there  ensues  much  more  promptly.  But,  on  the 
other  hand,  after  a  very  short  repose,  excitability  returns. 

I  will  not  dwell  upon  the  facts  which  seem  to  prove  that 
the  cortex  cerebri  may  give  rise  to  epileptiform  convul- 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.   69 

sions  (Hughlings  Jackson).  Vulpian  says  that  the  mani- 
festations in  partial  epilepsies  always  leave  a  considerable 
doubt  in  the  mind  ;  because,  although  a  lesion  may  be  dis- 
tinctly visible  in  the  cortex,  still  it  is  impossible  to  know 
if  the  epilepsies  really  proceed  from  it.  Partial  epilepsies 
often  exist  when  there  is  no  lesion  appreciable  either  to 
the  naked  eye  or  the  microscope.  The  experimental  epi- 
lepsy observed  by  Franck  fully  proves  the  excitability  of 
the  gray  substance. 

It  would  be  interesting  to  investigate  how  that  excite- 
ment is  modified  by  sanguiferous  tension.  The  influence 
of  the  brain  upon  sanguiferous  tension  has  heretofore  been 
investigated  ;  but  the  influence  of  arterial  pressure  upon 
the  excito-motor  power  of  the  brain  would  be  a  curious 
study. 

We  are  here  brought  to  a  consideration  of  the  method 
in  which  the  cortical  region  responds  to  electricity.  Hitzig 
has  especially  employed  direct  currents, which  afford  better 
results  than  the  induced,  interrupted  current  chosen  by 
Ferrier.  Of  the  two  poles,  the  anode  (positive)  acts  more 
energetically  than  the  cathode  (negative),  and  this  differ- 
ence is  more  marked  in  proportion  to  the  feebleness  of 
the  current.  Schiff  has  also  made  some  interesting  obser- 
vations upon  the  same  subject,  though  they  have  led  to 
a  theory  certainly  erroneous.1 

The  constant  current  acts  better  than  the  induced  ;  and 
of  the  induced  currents  the  open  one  is  best.  This  is  be- 
cause it  lasts  longer  ;  and  Schiff  says  that  for  the  sensa- 
tions a  certain  duration  of  excitement  is  necessary.  Motor 
responses,  he  says,  are  not  instantaneous,  but  require  the 
■g^-g  of  a  second  ;  whereas,  if  a  nerve  was  employed  as  the 
conductor,  the  interval  would  be  but  the  3-0V0  of  a  second. 
He  holds  that  it  consequently  involves  a  reflex  action. 

Now  this  conclusion  is  not  exact,  because  the  cortical 
substance  is  evidently  concerned  in  these  phenomena. 

1  Lezioni  sopra  il  systemo  nervoso  encefalico,  Firenze,  1S74,  et  lo  Speri. 
mentale,  xxxvii.,  p.  239,  xxxviii.,  p.  241. 

6 


JO  CEREBRAL   CONVOLUTIONS. 

A  very  important  problem  to  elucidate,  not  only  on  ac- 
count of  the  method,  but  in  a  general  physiological  point 
of  view,  is  the  influence  of  various  poisons  on  the  cerebral 
excitability. 

Hitzig  in  his  first  memoir1  has  shown  that,  in  animals 
etherized  or  under  the  infl  uence  of  morphine,  the  sigmoid 
gyrus  is  excitable.  He  concludes  by  saying  :  "  When  ani- 
mals are  profoundly  etherized,  though  all  traces  of  reflex 
action  have  disappeared,  the  electric  excitability  of  the 
brain  is  partlv  retained,  partly  lost.  On  the  contrary,  with 
morphine,  even  in  large  doses,  the  excitability  is  not  dimin- 
ished." 

Carville  and  Duret2  in  their  experiments  have  employed 
chloral  with  good  results,  it  giving  an  absolute  insensibility, 
though  preserving,  with  some  reduction,  the  cerebral 
excitability. 

Bochefontaine,3  in  a  remarkable  series  of  experiments, 
shows  that  with  the  use  of  curare,  which  completely  para- 
lyzes the  voluntary  muscles  without  affecting  those  of 
organic  life,  it  can  be  proved  that  the  brain  preserves  all 
its  excitability.  This  is  an  interesting  confirmation  of  the 
celebrated  experiments  of  Claude  Bernard,  and  it  is  seen 
that  curare  affects  the  nervous  system  only  as  it  is  con- 
nected with  the  muscles  of  animal  life.  Any  one  may 
satisfy  himself  that,  as  has  been  shown  by  Schiff,  when  an 
animal  is  in  a  profound  state  of  anaesthesia,  all  motor  re- 
action disappears,  the  bulb  only  exercising  its  functions. 
Upon  this  fact,  together  with  those  just  mentioned,  Schiff 
based  his  reasons  for  considering  the  movements  succeed- 
ing the  excitation  of  the  convolutions  as  movements  of 
reflex  origin,  a  theory  to  which  we  shall  recur.  We  only 
observe  that,  without  further  demonstration,  it  ought  not 
to  be  said  that  chloral  or  ether  affects  only  the  reflexes. 
■On  the  contrary,  it  very  probably  affects  all  the  nerve- 
elements. 

1  Loc.  cit.,  p.  401  -  Bull,  de  la  Soc.  de  Biol.,  1874,  p.  377. 

3  Arch,  de  physiol.,  1876,  p.  140. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.    J\ 

When  chloralization  has  been  pushed  to  the  extreme, 
the  bulb  is  the  only  vestige  of  nervous  life  retained  by  the 
torpid  animal,  and  by  it  are  maintained  the  rhythmic 
movements  of  respiration  ;  under  these  circumstances  it 
can  be  demonstrated  that  galvanization  of  the  brain  is  not 
without  effect.     The  following  experiment  affords  proof  : 

A  small,  lean  cat  was  etherized  and  tied.  Into  the  crural 
vein  I  injected  forty-seven  grains  of  chloral.  The  skull 
was  opened  and  the  crucial  fissure  laid  bare.  Excitation 
of  that  region  provoked  not  the  slightest  movement  of  the 
legs,  but  it  suspended  the  respiratory  rhythm.  In  differ- 
ent regions  of  the  cortex  cerebri  various  points  were  found, 
the  excitation  of  which  immediately  arrested  respiration. 
Notwithstanding  the  enormous  dose  of  chloral,  the  cat 
lived  and  respired  with  regularity  for  nearly  four  hours. 
At  various  times  we  verified  that  excitation  of  the  brain 
and  of  the  sciatic  would  arrest  respiration.  At  the  end  of 
three  hours  sciatic  excitation  was  without  effect.  A  little 
later  the  same  was  true  of  cerebral  excitation,  and  there- 
after the  strongest  electric  currents  had  no  apparent 
effects. 

We  may  hold,  then,  that  .the  respiratory  action  is  the 
last  to  fail  ;  for  when  the  excito-motor  power  of  the  limbs 
has  disappeared,  the  action  of  the  brain  upon  the  bulb 
remains  intact.  It  would  seem  that  the  excito-motor 
apparatus  of  respiration  is  the  last  to  be  paralyzed  by 
poisons,  both  in  the  bulb  and  the  cortex  cerebri. 

The  effects  of  asphyxia  on  cerebral  excitability  have  also 
been  sought,  but  the  results  are  not  very  concordant. 
Hitzig1  found  from  asphyxia  no  action  upon  the  excita- 
bility. 

1  Unters.  iiber  das  Gehirn,  Arch,  fur  Anat.,  1873,  P-  4°4- 


J2  CEREBRAL   CONVOLUTIONS. 


Sec.  2.    THERMIC,   ELECTRIC,   AND   CHEMICAL 
CONDITIONS  OF  THE  CONVOLUTIONS. 

Few  experiments  have  been  made  upon  the  electric  and 
thermic  state  of  the  convolutions.  Schiff l  and  Caton  - 
only  have  furnished  some  information  upon  the  subject. 
Schiff,  by  means  of  thermo-electric  apparatus,  has  proposed 
to  measure  the  rise  of  temperature  in  the  nerves  and  the 
nervous  centres  resulting  from  the  influence  of  various 
excitations.  I  regret  not  being  able  to  go  into  the  details 
of  these  remarkable  experiments  ;  I  will  give  the  conclu- 
sions only. 

Sensible  irritation  of  the  peripheric  nerves  produced  an 
increase  of  heat  in  the  brain  ;  excitation  of  the  special 
senses,  hearing,  smelling,  etc.,  had  same  result,  so  also 
with  vivid  impression,  unexpected  view  of  an  object.  In- 
deed, all  mental  activity  expressed  itself  by  augmented 
heat  in  the  cerebral  hemispheres. 

Other  authors  (Broca,  Voisin)  have  observed  the  tem- 
perature of  the  skull a  and  obtained  similar  results.  All 
lively  impressions  or  mental  labor  augmented  the  exterior 
heat  of  the  skull,  often  it  was  confined  to  one  side,  gener- 
ally the  left  (Broca). 

It  is  probable  that  this  difference  in  the  external  tem- 
perature corresponded  to  a  difference  of  temperature  in 
the  deep  parts  of  the  hemispheres. 

It  might  be  supposed  that  thermic  oscillations  belonged 

1  Arch,  de  phys.,  t.  iii.,  1870,  pp.  1,  198,  and  451. 

2  Brit.  Med.  Jour.,  28th  Aug.,  1875,  p.  278.  It  is  by  an  error  that  in  the 
Revue  des  Se.  méd.  the  quotation  from  Caton  is  translated  as  though  the  ex- 
periments had  been  made  by  Ferrier. 

3  Lombard,  Expériences  sur  l'influence  du  travail  sur  la  température  de  la 
tête,  analyse  dans  les  Arch,  de  physiol.,  1868,  t.  i.,  p.  670.  Broca,  Congrès 
de  1877.  Voisin,  Leçons  sur  les  maladies  mentales.  France  médic,  10  juillet, 
1878.     In  course  of  publication. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.    73 

to  change  of  cardiac  rhythm  or  to  a  difference  in  the  local 
tension  of  the  blood-vessels.  Schiff  rejects  the  first  propo- 
sition, but  is  not  so  sure  concerning  the  second. 

Whatever  hypothesis  may  be  adopted  concerning  the 
cause  of  these  thermic  phenomena,  the  fact  of  itself  is  very 
important  and  accords  with  that  which  we  know  concern- 
ing the  chemical  activity  of  the  encephalon.  Experiments 
of  some  date  back1  have  shown  that  cerebral  activity  in- 
creased the  production  of  carbonic  acid,  urea,  and  proba- 
bly also  cholesterine.  Consequently  the  nervous  excite- 
ment which  puts  into  activity  the  cerebral  cells  increases 
also  the  temperature  and  the  chemical  combustion. 

There  is  a  third  phenomenon  correlative  to  the  chemical 
phenomena,  that  is  the  variation  of  the  electric  condition 
of  the  brain.  It  has  been  observed  by  Caton  and  described 
in  a  short  note.  In  the  normal  state,  there  is  an  electric 
current  (positive)  which  goes  from  the  cortex  cerebri  to 
the  white  substance  (cut),  or  into  which  a  gal vano metric 
needle  (negative)  has  been  plunged. 

Those  points  in  the  cortex  cerebri  where  electrization 
induces  movements  of  the  head  and  neck,  and  which  in 
repose  are  positive,  Caton  has  observed  to  become  negative 
when  connected  with  the  white  section,  after  sensorial  ex- 
citations, especially  after  excitation  of  the  retina.  The 
current  changes  direction  and  develops  an  absolutely 
negative  variation  as  in  a  nerve  which  is  excited  and  the 
muscle  which  contracts.  1  have  repeated  this  experiment 
upon  a  chloralized  dog  with  Lippmann's  electrometer 
which  gives  such  precise  indications,  and  I  have  been  but 
partially  able  to  verify  these  statements.  It  is  true  that 
if  an  electrode  be  placed  at  the  surface  of  the  convolutions 
and  another  to  the  deep  parts,  there  will  be  found  to  exist 
an  electro-motor  power,  less  than  that  in  the  muscle  and 
considerably  more  than  that  in  the  skin  and  fibrous  tissues. 
But  in  exciting  the  sciatic,  I   have  been  able  to  discover 

1  Flint,  Journ.  de  l'Anat.,  t.  i.,  p.  565.      ityasson,  thèse  inaug.,  Paris. 


74  CEREBRAL   CONVOLUTIONS. 

no  variation  in  the  direction  of  the  cerebral  electro-motor 
current.  Perhaps  the  chloral-poisoning  has  prevented  the 
phenomenon.  However  it  may  be,  the  experiment  remains 
subject  to  repetition,  and  it  would  be  interesting  to  follow 
the  electric,  thermic,  and  chemical  variations  of  the  brain, 
under  the  influence  of  sensorial  or  sensitive  excitants. 

The  theory  of  these  phenomena  is  too  complex  to  be 
discussed  here.  To  my  mind,  the  theory  of  Dubois-Rey- 
mond  and  Pfliiger  is  perhaps  less  satisfactory  than  that  of 
Hermann,  who  explains  the  electric  variations  by  chemical 
combinations.  It  is  probable  that  the  electric  conditions 
depend  upon  increased  chemical  combustions,  correspond- 
ing to  increased  nervous  activity. 


Sec.  3.  CIRCULATION  IN  THE  CONVOLUTIONS. 

We  will  not  pretend  to  treat  of  cerebral  circulation  in  a 
complete  manner  ;  it  is  proper,  however,  to  speak  of  it  as 
connected  with  the  convolutions  which  are  supplied  with 
a  rich  and  highly  contractile  arterial  network. 

Very  precise  experiments  demonstrate  that  this  abun- 
dant circulation  is  necessary  to  maintain  the  life  of  the 
nerve-substance.  By  ligating  the  carotids  and  vertebral 
arteries,  encephalic  circulation  is  more  or  less  completely 
arrested1  and  with  it  the  phenomena  of  encephalic  activity 
cease. 

Generally  the  circulation  is  at  first  completely  abolished  ; 
after  a  little  it  becomes  re-established,  and  the  lives  of 
rabbits,  and  especially  of  dogs,  can  be  preserved  after  the 
four  arteries  supplying  the  encephalon  have  been  tied. 

Vulpian  has  employed  a  still  more  certain  process  for 

1  For  the  history  of  the  question  I  refer  to  the  work  of  M.  Couty,  Influence 
de  l'encéphale  sur  les  muscles  de  la  vie  organique.  Arch,  de  phys.,  1876,  p. 
673. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.    75 

the  purpose  of  suppressing  the  circulation,  not  only  in  the 
spinal  cord,  but  also  in  the  brain,  which  is  to  inject  the  ar- 
teries with  water  containing  a  pulverized  substance,  pow- 
der of  lycopodium  for  example,  which  serves  to  obstruct 
the  minute  encephalic  arteries.1 

From  this  process,  sensibility  and  voluntary  motion  dis- 
appear with  surprising  rapidity,  the  animal  remains  inert, 
the  bulb  alone  retaining  its  power  of  function. 

Vulpian  observed  that  in  the  spinal  cord  the  gray  sub- 
stance only  was  paralyzed,  the  white  preserving  its  normal 
conductibility. 

Resting  upon  these  fundamental  facts,  Couty  has  studied 
the  effects  of  cerebral  anaemia  from  arterial  obstruction,  and 
he  first  observed  that  this  kind  of  anaemia  did  not  affect 
the  peripheric  vessels,  though  galvanic  excitation  of  the 
cortex  cerebri  does  ;  consequently,  galvanic  excitation  acts 
some  other  way  than  as  a  simple  arterial  constrictor. 

This  is  worthy  of  note  ;  for  some  authors,  especially 
Brown-Séquard,  without  clearly  defining  his  opinion  upon 
the  effect  of  electric  excitation,  maintain  the  idea  of  vascu- 
lar constriction.  It  is  not  probable  that  he  still  holds  that 
opinion  as  concerns  galvanic  excitation  of  the  cortex  cere- 
bri. In  carefully  examining  the  cerebral  surface  when 
electricity  is  being  applied,  no  vascular  contraction  is  ob- 
served ;  on  the  contrary,  there  is  dilatation,  and  capillaries 
before  invisible,  increase  and  become  visible.  I  am  aware, 
however,  that  the  opposite  effects  have  been  seen,  but  I 
believe  those  to  be  complex  effects,  which  attentive  analy- 
sis can  unravel.  To  the  present  there  is  nothing  entirely 
positive  and  constant. 

Couty  has  made  another  deduction  from  these  experi- 
ments :  that  since  the  gray  substance  exercises  no  influence 
upon  the  vessels,  and  electricity  does,  therefore  electricity 
does  not  directly  influence  the  gray  substance.  The  de- 
duction is  reasonable,   but   as   it   is  always  necessary   in 

1  Leçons  sur  l'appareil  vaso-moteur,  t.  ii.,  1S75,  p.  11S. 


y6  CEREBRAL   CONVOLUTIONS. 

physiology  to  distrust  indirect  proofs,  it  would  be  better 
to  make  the  direct  experiment,  and  ascertain  if  the  cortex 
cerebri  of  the  animal  whose  encephalon  is  anasmied  by  the 
powdered  injection  is  still  excitable  by  electricity.  This 
alone  will  permit  a  rigorous  and  indisputable  conclusion. 

Be  this  as  it  may,  so  far  as  concerns  cerebral  function, 
we  see  that  complete  anasmia  rapidly  suspends  sensibility 
and  voluntary  motion. 

We  will  now  see  what  modifications  belong  to  normal 
cerebral  circulation. 

Attention  is  at  first  called  to  the  difficulties  of  experi- 
mentation. If  the  brain  of  an  animal  is  exposed,  contact 
with  the  air  will  excite  or  paralyze  the  vessels,  and  gener- 
ally produce  intense  congestion.  If  it  be  shielded  with  a 
glass  cover,  the  exuded  blood  and  fluids  prevent  seeing 
what  goes  on  ;  and  besides,  what  could  be  concluded,  for 
might  not  the  consecutive  encephalitis  be  a  source  of  error 
difficult  to  eliminate  ?  Moreover,  to  prevent  voluntary 
movements  of  the  animal,  which,  if  violent,  would  suddenly 
change  the  venous  pressure,  chloral,  morphine,  or  ether 
would  be  necessary,  and  consequently  no  conclusion  of  a 
certain  nature  could  be  arrived  at. 

Thus  we  have  recourse  only  to  indirect  proofs  or  to  in- 
conclusive experiments.  Physiological  knowledge  upon 
the  subject  is  as  yet  very  vague. 

Some  things,  however,  are  precisely  known.  Long  since, 
Claude  Bernard  '  observed  that,  after  section  of  the  great 
sympathetic,  the  hemisphere  of  that  side  was  warmer  than 
the  other.  In  this  respect,  the  arteries  of  the  brain  acted 
in  a  similar  manner  to  those  of  the  eye,  the  ear,  and  the 
face.  Vulpian"  repeated  these  experiments  by  exciting  in- 
stead of  cutting  the  sympathetic  nerve,  and  in  various  cases 
he  has  seen  the  vessels  contract  in  a  most  notable  manner. 

Nothnagel   states  that    excitation    of   the  sciatic  nerve 

1  Mém.  de  la  Soc.  de  Biol.,  1853,  p.  94. 

2  Loc.  cit.,  t.  i.,  p.  109  ;  t.  ii.,  p.  120  et  seq.  In  that  work  will  be  found  a 
complete  history  of  the  question  ;  it  is  therefore  needless  to  reproduce  it  here. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS,    yj 

causes  a  reflex  dilatation  of  the  vessels  of  the  pia  mater. 
But  that,  reflex  in  the  encephalic  capillaries  has  been  thrown 
in  doubt,  and  it  does  not  appear  to  me  that  the  matter  can 
be  considered  as  settled,  although  Regnard,  in  an  interest- 
ing work,1  states  that  he  has  seen  peripheric  excitations 
produce  cerebral  congestion  (Expér.  I.  et  III.). 

As  Vulpian  remarks,  excitation  of  the  sciatic  (after  sec- 
tion of  the  great  sympathetic)  often  causes  contraction  of 
the  vessels  of  the  ear,  and  the  same  phenomenon  is  proba- 
bly produced  in  the  vessels  of  the  encephalon.  It  is  possi- 
ble, then,  that  the  vaso-motor  action  upon  the  periphery  of 
the  vessels  from  the  pia  mater  may  induce  either  dilatation 
or  contraction,  according  as  the  great  sympathetic  is  in- 
tact or  not. 

In  its  pathological  aspect,  Brown-Séquard  thinks  that 
the  reflex  contraction  of  the  vessels  of  the  pia  mater  might 
produce  cerebral  excitation  and  consecutive  epilepsy  by 
anaemia.  This  theory  seems  controverted  by  that  which 
we  have  just  remarked,  concerning  the  immediate  paraly- 
sis of  the  excitability  of  the  brain  by  anaemia.  Besides, 
Ferrier  has  observed  that,  accompanying  an  epileptic  at- 
tack  produced  by  galvanic  excitation  of  the  cortex  cerebri 
of  an  animal,  the  surface  of  the  cortex  was  congested  and 
not  anasmied.  Vulpian  has  several  times  observed  the  same. 

Many  authors  have  dwelt  upon  the  relation  of  sleep  to 
encephalic  circulation.  It  has  been  supposed  that  sleep 
was  due  to  cerebral  congestion.  This  was  contested  by 
Durham,  who  made  the  first  regular  experiments  upon  the 
subject.2 

Removing  a  round  bit  of  the  skull,  he  laid  bare  the 
dura  mater  and  examined  the  brain.  From  his  experiments 
he  concluded,  that  during  normal  sleep,  the  brain  is  anae- 
mied  and  that  upon  waking  the  brain  became  congested, 
so  that  anasmia  was  either  the  cause  or  the  effect  of  sleep. 

Durham's  experiments  are,  to  be  sure,  few  and  open  to 

1  Thèse  de  Strasbourg,  1868. 

■  Physiology  of  Sleep.     Guy's  Hosp.  Reps.,  i860,  p.  14g  et  seq. 


78  CEREBRAL   CONVOLUTIONS. 

criticism.     I  would  remark  the  same  respecting  observa- 
tions made  upon  those  ill  or  wounded.1 

Regnard's  experiments  upon  chloroformed  animals 
prove  nothing  for  the  normal  state,  at  least  the  demonstra- 
tion is  insufficient.'2 

Flemming3  has  made  some  researches  which  seem  to 
confirm  the  theory  that  sleep  results  from  anaemia.  Strong 
pressure  upon  the  carotids  produces  a  passing  hyperesthe- 
sia, characterized  by  vertigo,  ringing  in  the  ears,  hyperi- 
deation,  analogous  to  that  in  sleep,  finally  sleep — sleep  and 
anaesthesia.  But  what  relation  is  there  between  these 
phenomena  and  real  sleep  ? 

Brown-Séquard  has  also  defended  the  theory  of  cere- 
bral anaemia  as  the  cause  of  sleep,  and  to  a  certain  degree 
he  assimilates  normal  sleep  to  a  light  attack  of  epilepsy. 
He  produces  an  ingenious  likeness,  but  a  phenomenon  of 
which  the  cause  is  not  known  cannot,  be  explained  by  a 
phenomenon  yet  more  mysterious.4  At  all  events,  the 
theory  of  anaemia,  supported  by  the  facts  of  Durham  and 
Flemming,  carry  no  more  conviction  than  other  facts 
which  would  seem  to  prove  the  contrary. 

The  direct  experiments  undertaken  for  the  purpose  of 
judging  the  condition  of  the  cerebral  surface  have  never 
given  uniform  results. 

Neither  Regnard,  Langlet,  Durham,  Hammond  nor  J. 
Cappie  5  have  ever  been  able  to  precisely  describe,  by  these 
methods,  the  condition  of  cerebral  circulation  during  sleep. 

Gubler6  thought  that  observation  of  the  pupils  would 
give  useful  indications.     In  fact,  it  is  admitted,  and  many 

1  Krauss,  Gaz.  hebd.,  1854. — Brown,  Am.  Jour.  Med.  Se,  1S61,  etc. 
'-'  See  the  excellent  thesis  of  Langlet,  Etude  critique  sur  quelques  points  delà 
physiologie  du  sommeil,  th.  inaug.,  Paris,  1872. 

3  Anœsthesia  by  Compression  of  the  Carotids,  Bull.  gén.  de  thérapeut.),  t. 
xlix.,  p.  37). 

4  For  an  exposé  of  these  opinions  by  Brown-Séquard,  consult  an  analysis 
which  he  has  given  of  Kussmaul  and  Tenner.     Jour,  de  Phys.,  t.  i.,  1858,  p.  201. 

5  The  Causation  of  Sleep,  Edinb.,  1S72. 

6  Gaz.  des  hôp.,  1S58. 


PHYSIOLOGICAL   PROPERTIES   OF   THE   CONVOLUTIONS.    79 

facts  seem  to  prove  it,  that  the  encephalic  circulation  and 
that  of  the  iris  are  allied,  congestion  of  the  first  always 
coinciding  with  irido-choroidian  congestion.  Now  when 
the  iris  is  congested,  the  pupil  is  contracted,  consequently 
contraction  of  the  pupil  is  a  sign  of  cerebral  congestion. 

In  normal  sleep  there  certainly  is  almost  always  contrac- 
tion of  the  pupil  ;  but,  as  I  have  before  said,  should  we 
not  exercise  prudence  in  accepting  indirect  proofs,  requir- 
ing a  series  of  reasoning  which  may  be  excellent  in  appear- 
ance, but  perhaps  in  reality  erroneous  ? 

To  affirm  that  a  thing  exists,  it  must  have  been  seen,  and 
unfortunately  it  has  not  yet  been  seen  in  normal  sleep,  un- 
complicated by  pathology  or  experiment,  whether  the 
brain  was  congested  or  angemied.  The  question,  then,  is 
in  dispute  and  the  protocol  incomplete. 

Thanks  to  registering  instruments,  science  has  lately 
been  enriched  by  some  valuable  knowledge  relative  to 
cerebral  circulation. 

Some  time  since,  Magendie,1  Bourgougnon,2  and  my 
father  3  studied  the  movements  of  the  brain  and  the  oscil- 
lations of  the  cephalo-rachidian  fluid.4 

These  labors  demonstrated  that  the  encephalon  becomes 
swollen  during  violent  respiratory  efforts,  and  that  cere- 
bral movements  depend  in  part  upon  the  cardiac  impulse 
and  partly  upon  the  respiratory  rhythm.  In  the  hands  of 
Salathé,  Franck,5  Mosso  and  Giaccomini,6  the  graphic 
method  has  given  very  remarkable  results,  which  confirm 
and  complete  the  opinions  of  previous  observers. 

Although  these  experiments  could  not,  as  was  realized 

1  Jour,  de  la  phys.,  t.  vi.,  et  t.  vii.,  1825. 

2  Th.  inaug.,  Paris,  1S35. 

3  Anat.  méd.  chir.,  1st  éd.,  1857. 

4  For  the  bibliography  see  the  very  complete  thesis  of  our  friend  Dr.  Salathé, 
Recherches  sur  les  mouvements  du  cerveau,  Paris,  1877.  The  major  part  of  the 
experiments  there  mentioned  may  be  found  in  the  Comptes  rendus  du  labora- 
toire de  M.  Marey,  for  1876. 

5  Researches  upon  Expansion  of  the  Brain.     Jour,  de  l'Anat.,  1877,  P-  207- 

6  Comptes  rendus  de  l'Acad.  des  Se,  3d  Jan.,  1877. 


SO  CEREBRAL   CONVOLUTIONS. 

by  Franck1  and  Salathé2  serve  to  settle  the  question  re- 
specting- the  circulatory  cause  of  sleep,  nevertheless  it 
gave  positive  facts  relative  to  arterial  tension  in  the  brain. 

The  following  are  the  principal  facts  thus  brought  for- 
ward : — 

i  st.  In  repose,  in  absence  of  all  effort,  movements  of  the 
brain  do  not  correspond  to  the  respiratory  rhythm  ;  only 
to  the  arterial  rhythm. 

2d.  Each  systole  of  the  heart  increases  the  volume  of 
the  brain,  a  kind  of  congestion. 

This  fact  respecting  the  brain  is  analogous  to  that  which 
Piégu,  Mosso,  and  especially  Franck  have  observed  in 
various  other  parts  of  the  body,  only  on  account  of  the 
enormous  vascularity  of  the  cortex  cerebri  the  phenome- 
non is  there  much  more  emphasized. 

3d.  Inspiratory  and  expiratory  efforts  greatly  change 
the  movements  and  volume  of  the  brain.  Expiration  and 
effort  augment  its  volume,  inspiration  greatly  diminishes 
it.     Compression  upon  the  veins  of  the  neck  increases  it. 

4th.  The  cephalo-rachidian  liquid  is  the  moderator  or 
safety-valve  which  protects  the  distended  cerebral  pulp  from 
pressure  against  the  skull-walls  (A.  Kichet). 

We  reconsider  these  facts  first,  because  they  are  the 
only  positive  ones  which  we  possess  relative  to  cerebral 
circulation,  and  also  that  cerebral  circulation  is  in  reality 
the  circulation  of  the  convolutions.  The  white  matter  has 
little  vascularity,  and  the  central  gray  masses  have  a  vol- 
ume greatly  inferior  to  the  cortex  cerebri.  It  may  be  said 
that  about  half  of  the  blood  sent  to  the  encephalon  is  dis- 
tributed to  the  cortex. 

The  convolutions,  then,  do  not  always  contain  the  same 
quantity  of  blood  ;  with  each  action  of  the  heart  it  varies, 
but  this  variation  produces  no  functional  disturbance. 

The  knowledge  furnished  by  pathology  relative  to  cere- 
bral congestion  or  anaemia  is  of  minor  value  (heart  disease, 
maladies  of  the  great  sympathetic,  migraine,  disorders  of 
sleep,  plethora,  etc.),  and  we  will  not  here  discuss  it. 

1  Loc.  cit.,  p.  285.  *  Loc.  cit.,  p.  48. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  8 1 


CHAPTER  II. 
FUNCTIONS  OF  THE  CONVOLUTIONS. 

Unfortunately  we  cannot  treat  of  this  vast  question  in 
its  entirety.  We  will  attempt,  however,  to  bring  out  the 
positive  points  which  the  various  methods  of  investigation 
have  given  to  science. 

Convolutions  can  be  said  to  have  three  principal  func- 
tions :  motion,  sensation,  and  intellection  ;  we  will  examine 
them  successively. 


Sec.  i.  FUNCTION  OF  MOTION. 

A.    METHODS   OF   INVESTIGATION. 

Method  by  excitation. —  We  have  before  spoken  of  the 
methods  of  electrizing  certain  portions  of  the  cortex  cere- 
bri.    Some  points  only  remain  to  be  noticed. 

a.  The  current  must  not  be  too  strong. 

b.  The  electrodes  should  be  near  together. 

c.  Care  should  be  taken  that  the  surface  is  not  covered 
with  blood. 

Without  all  these  precautions  there  is  greater  liability 
to  diffusion,  and  therefore  the  conclusions  cannot  be  so 
exact. 

Furthermore,  shaking  of  the  brain,  loss  of  blood,  pro- 
longed exposure  of  the  convolutions  to  the  air,  should  be 
avoided. 

The  results  of  different  experiments  cannot  be  considered 
as  susceptible  of  comparison  unless  the  experimental  con- 
ditions have  been  the  same.  (Chloroform,  chloral,  mor- 
phine, etc.). 


82  CEREBRAL   CONVOLUTION'S. 

Electric  excitation  is  an  excellent  process,  but  as  it  is 
subject  to  various  grave  objections  it  should  be  corrected 
by  other  methods. 

Method  by  destruction. — Abrasion  was  first  employed  by 
Fritsch  and  Hitzig.  Upon  removing  with  the  bistoury  a 
thin  bit  of  cerebral  substance,  paralyses  follow.  These 
have  been  especially  studied  by  Carville  and  Duret. 

The  cerebral  bit  may  be  taken  away  with  a  scraper  in 
place  of  a  bistoury,  or  still  better,  may  be  cauterized  with 
a  hot  iron.  According  to  Carville  and  Duret  all  these 
processes  give  about  the  same  results.  These  authors 
have  shown  that  dogs  so  operated  upon  present  certain 
paralyses,  or  rather — the  loss  of  motion  being  incomplete — 
pareses. 

A  second  method  has  been  employed  by  Fournie,1  Noth- 
nagel,2  and  Beaunis.3  This  consists  in  the  injection  of  a 
caustic  liquid  (chloride  of  zinc,  perchloride  of  iron,  chro- 
mic acid)  serving  to  destroy  the  cerebral  parts  with  which 
it  comes  in  contact. 

On  account  of  the  diffusion  of  liquids  and  consecutive 
inflammation,  it  is  doubtful  if  this  method  gives  good 
results,  at  least  for  the  cortex,  though  respecting  the  cor- 
pora striata  and  the  optici  thalami,  interstitial  injections 
seem  to  have  rendered  Nothnagel  some  tolerably  precise 
facts. 

Along  with  interstitial  injections  should  be  placed 
Goltz's  method  of  injecting  compressed  water  into  differ- 
ent points  of  the  hemisphere.  This  process,  which  destroys 
the  cortex  upon  a  somewhat  extended  scale,  does  not  seem 
adapted  to  determining  the  motor  regions  of  the  convo- 
lutions. 

The  third  method  we  have  before  spoken  of,  it  is  that  of 
Vulpian  and  Couty. 


1  Experimental  Researches  upon  the  Functions  of  the  Brain.      Paris,  1873. 
■  Virchow's  Arch.,    t.  lvii. ,  lviii.,  lx. ,  and  Ixii.  ;  Experimentelle  Untersuchur 
gen  uber  die  Functionen  des  Gehirns. 
3  Traité  de  phys.,  1876,  note  5,  p.  1101. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  83 

It  consists  in  injecting  powdered  lycopodium  and  then 
examining  the  condition  of  the  arteries  in  the  brain,  to 
ascertain  precisely  the  cerebral  regions  which  have  been 
anaemied. 

Experimental  process,  to  a  certain  degree,  makes  known 
to  us  the  general  influence  of  the  encephalon,  but  for  pre- 
cisely localizing  a  phenomenon  as  originating  in  a  certain 
convolution  or  in  a  specified  region,  it  is  doubtful  if  this 
method  is  sufficient  ;  but  it  may  always  serve  as  a  means 
for  correction. 

In  short,  the  method  of  superficial  destruction,  either  bv 
bistoury  or  red-hot  iron,  and  that  of  electric  excitation  are 
those  which  have  given  and  will  give  the  greatest  services. 
Thev  have  their  inconveniences,  but  we  know  nothing 
better. 


B.    ACTION    OF    THE    CONVOLUTIONS    UPON    THE    MUSCLES 
OF  ANIMAL   LIFE. 

When,  as  in  the  experiments  of  Fritsch  and  Hitzig,  the 
superficial  part  of  a  dog's  encephalon  is  excited  by  a 
moderate  electric  current  that  half  of  the  body  opposite 
to  the  hemisphere  excited  will  exhibit  movements,  vary- 
ing according  to  the  points  excited  and  differing  somewhat 
also  as  the  experimental  conditions  may  differ. 

The  general  character  of  movements  thus  induced  differ 
considerably  from  those  produced  by  excitation  of  the 
nerves  or  muscles.  They  are  combined  movements, 
limited  to  a  group,  or  rather  to  a  muscular  function.  They 
appear  as  if  destine'd  to  some  use.  Besides  this,  they  are 
much  slower  and  more  feeble  than  movements  occasioned 
by  direct  nerve  or  muscular  excitation. 

The  exact  limitation  of  the  action  from  motor-centres 
interests  the  physiologist  less  perhaps  than  the  medical 
practitioner  ;  much,  however,  has  been  written  on  the 
question. 

The  following  cut  gives  an  idea  of  the  centres  found  by 


84 


CEREBRAL   CONVOLUTIONS. 


Fritsch  and  Hitzig,  and  the  explanatory  text  beneath  suf- 
ficiently conveys  their  opinion. 


Fig.  13. — A  dog's  brain,  serving  to  explain  the  researches  of  Fritsch  and 
Hitzig. 

Triangle,  motor-centres  of  muscles  of  the  neck.  Cross  and  dot,  centre  of 
extensors  and  adductors  of  fore-leg.  Cross,  centre  of  flexion  and  rotation  of 
fore-leg.     Quadruple  cross,  centre  of  hind-leg.     Circle,  centre  of  facial  nerve  (?). 


•uric   I 


Fig.  14. — Right  hemisphere  of  dog's  brain  (after  Ferrier). 
A,  Fissure  of  Sylvius.     B,  Crucial  furrow.     O,  Olfactive  bulb.     I.,  IL,  III., 
and  IV.,  first,  second,  third,  and  fourth  convolutions. 

The  first  result  acquired  by  Fritsch  and  Hitzig,  and  con- 
firmed by  Ferrier,  Carville,  Duret,  and  many  others,  is 


FUNCTIONS   OF   THE   CONVOLUTIONS.  85 

that  only   the  region  surrounding  the   crucial  furrow  is 
motor. 

To  this  rule,  however,  there  are  some  exceptions.  Ac- 
cording to  Hitzig,  movements  of  the  muscles  of  the  neck 
could  be  excited  at  the  point  indicated  by  the  triangle, 
though  these  movements  were  not  produced  with  con- 
stancy. Ferrier,  in  his  numerous  and  interesting  experi- 
ments, differs  somewhat  from  Hitzig.  The  preceding  cut 
(fig.  14)  illustrates  the  localizations  given  by  Ferrier: 
1.  The  hind  leg  is  advanced  as  for  walking. 

3.  Undulatory  motion  of  the  tail. 

4.  Retraction  and  adduction  of  fore-leg. 

5.  Elevation  and  forward  movement  of  shoulders. 

7.  Movements  of  the  eyes. 

8.  Retraction  of  angle  of  the  mouth. 

9.  Opening  of  the  mouth  and  barking. 

1 1.  Retraction  of  angle  of  the  mouth. 

12.  Opening  of  the  eyes;  head  turns  to  the  opposite 
side. 

13.  Eyes  turn  to  the  opposite  side. 

14.  Ear  becomes  erect. 

15.  Twisting  of  nose  to  the  same  side  (?). 

These  experiments  have  been  repeated  upon  jackals  and 
cats,  and  even  upon  animals  where  the  convolutions  are 
scarcely  developed.  They  have  no  great  interest  though, 
especially  as  the  exact  localization  of  these  excitations,  as 
related  to  the  resulting  movements,  is  in  no  way  certain. 

Experiment  has  been  made  upon  the  monkey  by  Hitzig 
and  frequently  repeated  by  Ferrier.  In  the  following  cut 
Ferrier  has  represented  the  various  excitable  points  of  the 
cortex  cerebri  of  the  monkey  : — 

1.  Leg  advances  as  in  walking. 

2.  Complex  movements  of  thigh,  leg,  and  foot. 

3.  Movement  of  tail. 

4.  Retraction  and  adduction  of  arm. 

5.  Forward  extension  of  arm  and  hand. 

6.  Supination  and  flexion  of  fore-arm. 

7 


86 


CEREBRAL   CONVOLUTIONS. 


7.  Zygomatic  action,  drawing  the   mouth  backwards 
and  upwards. 

8.  Elevation  of  ala  of  the  nose  and  upper  lip. 

9  and  10.  Opening  of    mouth  with  protrusion  (9)  and 
retraction  (10)  of  the  tongue. 


Fig.  15. — Lateral  hemisphere  of  the  monkey  (after  Ferrier). 


12.  Eyes  open  and  turn  to  opposite  side,  pupils  dilate. 

13.  Eyes  turned  to  opposite  side,  raised  (13),  lowered 
(13').     Pupils  contracted. 

14.  Pricking  of  opposite  ear,  pupils  dilated,  head  and 
eyes  turned  to  opposite  side. 

On  account  of  the  similarity  between  the  monkey's  brain 
and  that  of  man,  experiments  made  upon  the  monkey  may 
serve  to  determine  the  motor-centres  in  man,  and  Ferrier 
has  indicated  upon  the  preceding  schematic  figure  how 
his  experiments  may  be  applied  to  the  human  subject.1 

In  the  monkey,  excitations  about  the  fissure  of  Rolando 
give  the  same  results  as  excitations  of  the  sigmoid  gyrus 
in  the  dog.  Elsewhere,  at  the  periphery  of  the  occipital, 
or  even  the  frontal  lobes,  no  movement  follows. 

The  question  is  less  simple,  however,  than  one  would  at 
first  believe,  and  is  not  settled  so  but  that  there  still  re- 
main uncertainties. 


1  Functions  of  the   Brain,   French  trans,  by  Duret,  1878,  p.  222.     English 
Edition,  p.  304. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  87 

Thus  Hitzig,1  in  other  experiments,  seemed  inclined  to 
believe  that  the  anterior  portion  of  the  sigmoid  gyrus  (that 
which  in  his  design  responds  nearly  to  the  letter  N,  and 
the  sign  A),  is  not  excitable  by  electricity,  and  may  be 
removed  without  producing  paralysis.  The  posterior 
part  of  the  gyrus  (that  corresponding  to  E,  and  1,  5,  and 


Fig.   16. — Lateral  view  of  human  brain.      (Letters   same  as  for  preceding 
cut.) 

4  of  cut  14),  on  the  contrary,  cannot  be  destroyed  without 
consequent  paralysis.  With  this  paralysis  there  is  a  series 
of  complex  phenomena,  difficult  to  disentangle,  and  which 
Schiff  calls  ataxia,  and  which  Hitzig  considers  as  signifi- 
cant of  the  abolition  of  muscular  sensibility  ;  besides  the 
phenomena  of  paralysis  (absence  of  energy,  will),  there  are 
also  phenomena  of  special  anaesthesia,  particularly  muscular 
ansesthesia. 

1  Neue  Untersuchungen,  Arch,  fiir  Anat.,  1S74,  p.  432. 


88  CEREBRAL   CONVOLUTIONS. 

Marcacci  '  has  recently  observed  that  the  excitable  zone 
of  the  sheep's  brain  is  chiefly  in  front  of  the  crucial  fissure, 
where  there  are  four  distinct  centres,  one  for  movements 
of  the  fore-legs,  one  for  the  neck,  one  for  the  face  and 
tongue,  and  one  for  the  movements  of  the  jaw.  No  dis- 
tinct centre  is  found  for  movements  of  the  hind  legs. 

According  to  Ferrier,  the  anterior  part  of  the  sigmoid 
gyrus  produces  movements  either  in  the  head,  eyes,  or 
neck.  I  will  add,  that  in  experiments  made  with  Boche- 
fontaine,  we  have  confirmed  this  statement,  and  we  have 
also  observed  that  with  quite  moderate  currents,  move- 
ments were  induced  either  in  the  eyes  or  eyelids. 

We  have  seen  electrization  of  the  anterior  part  of  the 
sigmoid  gyrus  of  a  chloralized  dog  provoke  contraction  of 
the  orbicularis  palpebrare  of  the  same  side,  and  this  where 
the  influence  of  the  dura  mater  was  out  of  the  question,  as 
it  was  cut  to  a  considerable  distance,  and  upon  being  ex- 
cited did  not  induce  the  same  reflex. 

Another  fact  seems  to  prove  that  there  is  not  in  the 
manifestation  of  any  given  movement  the  regularity  sought 
for.  Indeed,  with  the  same  dog,  the  electric  excitation  at 
the  same  point  back  of  the  crucial  furrow,  without  chang- 
ing position  of  the  electrodes,  we  have  frequently  seen 
were  dependent  upon  the  strength  of  the  current,  move- 
ment of  the  fore-leg,  movement  of  the  hind-leg  (with  very 
feeble  movement  of  the  fore-leg),  and  a  very  forcible  move- 
meni  of  both  fore  and  hind-legs. 

Consequently,  absolute,  inflexible  localization  of  the 
motor-zones  is  all  but  impossible.  There  are  zones  which 
encroach  upon  each  other,  but  none  of  these  zones  have 
limits  of  determined,  rigorous  constancy.  The  best  proof 
of  this  is  the  difference  existing  among  authors. 

If  I  were  to  venture  an  opinion  on  the  subject,  I  should 
say  that  so  far  as  concerns  details,  the  point  is  of  small  im- 
portance.    It  is  of  no  special  importance  to  know  if  there 

1  Arturio  Marcacci,  in  Rendiconto  delle  ricerche  sperimentali  eseguite  nel 
gabinetto  di  fisiologia  délia  R.  Universita  di  Siena.     Milan,  1S76. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  89 

is  a  centre  for  the  ear,  and  exactly  how  many  millimetres 
it  is  distant  from  the  centre  for  the  pupil.  That  which  is 
important  is  to  know  if  there  certainly  are  centres  for 
certain  determined  movements. 

It  is  already  proved  (as  respects  the  dog)  that  the  pos- 
terior part  of  the  crucial  furrow  is  the  eminently  excitable 
region  ;  above  for  the  hind  legs,  below  for  the  fore-legs. 

Concerning  centres  for  other  muscular  movements,  I 
refer  to  Ferrier's  work.  Their  existence  is  more  question- 
able and  additional  investigation  is  evidently  necessary. 

We  need  not  here  consider  the  excitation  of  the  surface 
of  the  cerebellum  from  which  Ferrier  observed  movements 
of  the  eyes,  we  would  only  remark  that  the  phenomena  of 
diffusion  towards  the  bulb  ought  to  be  more  pronounced 
than  that  following  the  excitation  of  the  hemispheres. 

Electricity  not  having  given  entirely  indisputable  re- 
sults,1 the  adjunct  of  another  process  has  naturally  been 
sought  ;  that  of  abrasion. 

According  to  Carville  and  Duret,  this  operation  gives 
the  following  results  : — 

1  st.  The  paralysis  is  limited  to  a  well-defined  group  of 
muscles. 

2d.  It  is  intermittent. 

3d.  It  disappears  at  the  end  of  five  or  six  days. 

Generally  the  paralysis  is  not  complete,  it  is  a  sort  of 
lameness,  so  that  the  dog  operated  upon  cannot  bring  the 
foot  to  place  and  so  walks  upon  the  back  of  it.  Goltz 
remarked  that  the  dogs  could  not  give  the  paw,  but  that 
in  combined  movements  they  contracted  the  muscles  very 
well,  when  such  movements  were  induced  by  the  reflexes. 

Schiff  has  dwelt  upon  the  exhibition  of  ataxia  and  con- 
secutive movements  resulting  from  ablations  of  the  cortex, 
which  he  compares  to  the  phenomena  arising  from  section 
of  the  posterior  columns  of  the  spinal  cord.2 

1  See  that  before  said,  p.  65  et  seq. 

■  Account  of  similar  phenomena  will  be  found  in  the  memoirs  of  Goltz,  Ueber 
die  Verrichtungen  des  Grosshirns,  Pfliiger's  Arch.,  t.  xiii.,  and  of  Hitzig,  Neue 
Folge,  etc.,  Arch,  fur  Anat.,  1876,  p.  692. 


90  CEREBRAL   CONVOLUTIONS. 

Albertoni  and  Michieli  '  from  their  labors  have  given 
the  following  results  : 

A.  In  rare  cases  there  is  no  paralysis,  though  the  opera- 
tion has  been  exactly  at  the  sigmoid  gyrus. 

B.  The  effects  are  more  pronounced,  defined,  and  dura- 
ble with  dogs  than  with  rabbits. 

C.  Paresis  in  dogs  diminishes  upon  the  next  day  after 
operation,  with  rabbits  it  has  by  that  time  entirely  disap- 
peared, and  at  the  end  of  four  or  five  days  it  disappears  in 
the  dog. 

It  seems  certain  that  in  some  cases  there  are  more  or 
less  extensive  destructions  of  the  motor  region  of  a  cere- 
bral hemisphere  without  consequent  paralysis.  Upon  this 
subject  may  be  recalled  an  experiment  of  Renzi's,  cited  in 
their  remarkable  work  by  Lussana  and  Lemoigne.2  It  is 
stated  that  the  power  of  standing  was  unimpaired,  but  the 
body  was  inclined  to  the  right  side. 

The  instance  published  by  Bochefontaine  3  is  still  more 
significant.  "  Vulpian,  in  one  of  his  lectures  of  the  course 
of  1875,  repeated  upon  several  dogs  the  experiments  of 
Hitzig.  In  one  the  operation  terminated,  the  wound  was 
stitched  up,  and  there  was  found  complete  absence  of 
paralysis.  The  animal  was  kept  ;  some  days  after  he  was 
bitten  by  a  another  dog,  the  sutures  were  torn  out,  and  a 
portion  of  the  brain,  in  appearance  like  a  reddish  pulp, 
protruded  through  the  opening  in  the  skull.  The  wound 
healed  without  trouble,  and  for  two  months,  during  which 
the  dog  was  kept  under  observation,  there  was  no  paraly- 
sis." 

The  results,  then,  of  the  method  by  abrasion  are  : 

A.  With  a  great  majority  of  dogs,  the  ablation  of  the 
convolutions  of  the  gyrus  produces  paralysis. 

B.  These  paralyses  are  transitory. 

C.  With  a  small  number  of  dogs  there  are  no  paralyses. 

1  Lo  Sperimentale,  Feb.,  1876. 

2  Des  centres  moteurs  encéphaliques,  1877,  Arch,  de  phys.,  p.  121. 

3  Bull,  de  la  Soc.  de  Biol.,  1875,  p.  387. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  QI 

Now  as  to  the  phenomena  resulting  from  pathological 
causes. 

1  st.  There  are  a  certain  number  of  instances  (very  few, 
however)  in  which  an  entire  cerebral  hemisphere  has  been 
destroyed  without  effecting  paralysis.  Several  cases  may 
be  cited.  In  a  few  words  T  will  condense  the  following  one 
borrowed  from  Prof.  Porta  and  recounted  by  Lussana  and 
Lemoigne.1 

"A  young  woman  had  an  abscess  upon  the  forehead  .  .  .  by 
use  of  a  sound,  destruction  of  the  corresponding  lobe  could  be 
recognized. 

During  the  last  three  days  of  her  life,  to  the  last  moments, 
when  convulsions  and  coma  terminated  life,  the  s?d?j'ect  retained 
her  mental,  sensorial,  and  motor  faculties  as  entire  as  though 
the  brain  had  been  uninjured.  Post-mortem  revealed  the  right 
hemisphere  entirely  suppurated,  that  is,  converted  into  a  yellow- 
ish-gray puriform  substance  .  .  .  entirely  disorganized  and  de- 
stroyed." 

As  it  is  not  my  intention  to  enter  pathology,  except  so 
far  as  it  will  serve  physiology,  I  will  not  recite  other  analo- 
gous cases  which  may  be  found  (few,  to  be  sure,  are  well 
authenticated)  in  the  old  archives  of  surgery  or  in  the  bul- 
letins of  the  Anatomical  Society,2  etc.  As  Charcot  says, 
very  many  of  the  reports  of  cases  are  without  value,  but  it 
would  be  difficult  to  deny  the  truth  of  all. 

Thus,  with  the  human  subject,  as  with  the  dog,  there  are 
exceptions  to  the  general  and  well-established  law,  that 
destruction  of  certain  parts  of  the  cortex  results  in  par- 
alysis of  certain  muscles. 

2d.  The  characters  of  these  paralyses  are  the  same  as 
those  of  experimental  paralysis,  and  1  can  do  no  better 
than  to  repeat  the  words  of  Charcot.3     "  There  are  hemiplc- 

1  Loc.  cit.,  p.  122. 

-See  also  the  memoir  by  Brown-Séquard  in  les  Arch,   de  physiol.,    1877 
P-  655. 

3In  the  thesis  inaug.  of  M.  Landouzy,  Paris,  1876,  p.  56;  Convulsions  et 
paralyses  liées  aux  méningo-encephalites. 


92  CEREBRAL   CONVOLUTIONS. 

gias  which  may  be  called  cortical,  in  contradistinction  to  those 
called  central.  The  cortical  paralyses  are  limited,  transient, 
and  variable  ;  the  central  paralyses  total,  embracing  the  entire 
one-half  of  the  body,  and  always  presenting  the  same  characters  ; 
cortical  paralysis  is  abnormal,  partial,  so  that  it  may  be  a  mon- 
oplegia or  may  include  the  surface  only  y 

These  curious  modifications  of  cortical  motor-innervation 
will  be  examined  further  on,  in  the  theory  of  these  phe- 
nomena. 

Some  questions  are  yet  to  be  resolved,  for  which  pathol- 
ogy furnishes  valuable  knowledge. 

i st.  Can  lesion  of  a  convolution  or  of  a  very  limited  re- 
gion of  the  cortex  cerebri  of  itself  produce  paralysis  ? 

We  could  cite  a  great  number  of  cases,1  but  we  will  con- 
tent ourselves  with  recalling  the  following  very  clear  one  : 

Without  loss  of  consciousness,  a  consumptive  was  affected  wit  Ji 
a  sudden  weakness  of  the  left  arm.  The  feebleness  increased 
until  death,  which  occurred  on  the  fourth  day  after.  The  par. 
alysis  was  much  more  pronounced  in  the  fore-arm  than  in  the 
arm,  and  especially  in  the  muscles  supplied  by  the  radial  nerve. 
No  sensorial  disturbance. 

AUTOPSY. — A  tubercle,  the  size  of  a  millet  seed,  was  found 
imbedded  in  the  cortex,  surrounded  by  a  zone,  one  centimetre  in 
diameter,  of  red  softening.  The  lesion  was  located  upon  the 
posterior  border  of  the  fissure  of  Rolando  {ascending  parietal 
convolution),  five  centimetres  and  a  half  from  the  zipper  border 
of  the  Jiemispliere.     The  brain  was  otherwise  absolutely  sound? 

2d.  Where  are  the  pathological,  alterations  of  the  cortex 
located  which  produce  paralyses  ? 

1  See  Charcot  and  Pitres  : — Contribution  à  l'étude  des  localisations  dans 
l'écorce  des  hémisphères  du  cerveau  ;  in  Revue  mens,  de  méd.  et  chir.,  1877, 
Nos.  ii.,  iii.  Bourdon  : — Rech.  Clin,  sur  les  centres  moteurs  des  membres,  in 
Bull,  de  l'Acad.  de  méd.,  1875,  2d  série,  t.  vi.,  No.  43. — Foville  :  Ann.  méd. 
psych.,  t.  xvi.,  Jan.,  1877.  Bull,  de  la  Soc.  anat.,  1875,  1876,  1877,  1878.  Bull, 
de  la  Soc.  Biol.,  1876,  1877,  1878. — Lépine,  in  Revue  mens,  de  méd.  et  de  chir., 
mai,  1877. — Ferrier,  British  Med.  Jour.,  March  and  April,  187S. — Bull,  de 
l'Acad.  méd.,  1877,  observations  of  Lucas. — Championnière,  Terrillon,  et 
Proust,  reported  by  Gosselin. 

8  Maurice  Reynaud: — Bull,  de  la  Soc.  anat.,  25  juillet,  1876. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  93 

Observations  of  cerebral  pathology,  to  a  certain  degree 
confirm  the  doctrine  of  cortical  localizations.  In  the  last 
few  years,  a  large  number  of  cases  have  been  adduced  and 
a  very  exact  representation  of  the  present  aspect  of  the 
question  may  be  found  in  the  formulated  conclusions  clos- 
ing the  Mémoire  by  Charcot  and  Pitres  ;'  they  are  deduced 
from  the  observations  contained  in  the  work: — 

a.  The  cortex  cerebri  is  not  functionally  homogeneous  ; 
only  one  part  is  concerned  in  the  regular  exercise  of  vol- 
untary motion.  That  part,  which  may  be  called  the  cor- 
tical motor-zone,  includes  the  paracentral  lobule,  the  frontal 
and  parietal  ascending  convolutions,  and  perhaps  also  the 
foot  of  the  frontal  convolutions. 

/;.  No  cortical  lesions,  whatever  their  extent,  situated 
outside  the  motor-zone,  affect  the  power  of  motion. 

c.  On  the  other  hand,  destructive  lesions,  even  very 
limited,  which  affect  either  directly  or  indirectly  the  mo- 
tor-zone, necessarily  entail  disturbance  of  voluntary  mo- 
tion. 

Pitres2  has  shown  that  lesions  involving  the  centrum 
ovale  are  not  manifested  by  motor  disturbances  unless  they 
affect  the  fasciculi  subjacent  to  the  zone  of  cortical  motor- 
centres  (fronto-parietal  fasciculi)  ;  if,  however,  they  affect 
the  prefrontal,  occipital,  or  sphenoidal  fasciculi,  they  pro- 
duce no  motor  trouble.  He  holds  that  the  fibres  composing 
the  fasciculi  of  the  centrum  ovale  are  conductors,  a  section 
of  which  prevents  manifestations  from  the  cortical  centres, 
as  absolutely  as  the  cutting  of  a  telegraphic  wire  interrupts 
the  current  for  telegraphy  and  renders  useless  the  galvanic 
battery. 

Such,  in  a  general  way,  is  the  topography  of  the  corti- 
cal motor-zone.  But  would  it  not  be  possible  to  determine 
somewhat  more  precisely  the  motor-centre  of  such  or  such 

1  Loc.  cit.,  p.  456. 

■  Recherches  sur  les  lésions  du  centre  ovale  et  des  hémisphères  cérébraux 
étudiées  au  point  de  vue  des  localisations  cérébrales.  Thèse,  Paris,  1877. — See 
also  Ballet,  Gaz.  méd.,  1878,  No.  2. 


94  CEREBRAL   CONVOLUTIONS. 

a  limb  or  of  the  various  muscular  groups?  Examination 
of  facts  has  enabled  Charcot  and  Pitres  to  say  that  the 
cortical  motor-centres  for  the  opposite  limbs  are  situated 
in  the  paracentral  lobule,  and  in  the  upper  two-thirds  of 
the  ascending  convolutions  ;  and  that  centres  for  facial 
movements  are  situated  in  the  lower  third  of  the  ascend- 
ing convolutions,  in  the  neighborhood  of  the  fissure  of 
Sylvius. 

Though  in  fact  this  only  concerns  the  lower  part  of  the 
face,  inasmuch  as  cerebral  lesions  give  rise  to  a  hemiplegia 
which  is  always  limited  to  the  lower  portions  of  the  face, 
the  superior  parts  remaining  free  (orbicularis  palpebra- 
rum, superciliaris,  frontalis),  a  symptomatic  dissociation 
which  gives  us  a  right  to  seek  a  correlative  anatomical 
dissociation. 

It  is  probable  that  the  centre  for  isolated  movements  of 
the  upper  extremities  is  located  in  the  middle  third  of  the 
ascending  frontal  convolution.  The  exact  situation  of  the 
cortical  motor-centres  for  the  nape  of  the  neck,  the  neck, 
the  eyes,  and  the  eyelids  is  not  at  present  known.1 

Respecting  instances  of  united  deviation  of  the  head  and 
eyes  from  hemispheric  lesion,  there  is  at  present  no  abso- 
lutely satisfactory  solution. 

Is  paralysis  a  necessary  consequence  of  destruction  of 
the  motor-zone  ?  Charcot,  as  will  be  seen,  says  yes.  But 
such  is  not  the  opinion  of  all  physiologists.  Vulpian  and 
Brown-Séquard  cite  some  exceptions  to  the  rule,  and  re- 
mark that,  if  there  exist  cortical  centres,  their  suppression 
ought  invariably  to  entail  a  loss  of  their  function.  Fur- 
ther on,  this  question  will  be  examined  as  relates  to  supple- 
mentation. 

The  three  questions  which  have  been  proposed  may  be 
answered  thus  : 

i st.  Cortical  lesion  alone  can  produce  a  permanent  or  a 
transitory  paralysis. 

1  Notwithstanding  an  observation  of  Grasset's,  Progrès  méd.,  27  mai,  1876, 
p.  431.     See  also  Landouzy,  Arch.  gén.  de  méd.,  1877,  août. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  95 

2d.  Cortical  lesion  produces  paralysis  only  when  it  is 
seated  in  the  motor-zone. 

3d.  All  cortical  lesions  of  the  motor-zone  produce  paral- 
ysis (there  are  exceptions  to  this  law). 

An  important  discovery  confirms  these  different  results  ; 
that  is,  descending  sclerosis  from  the  brain  ;  it  has  been 
shown  that  in  certain  lesions  of  the  motor-zone  there  was 
sclerosis  of  the  spinal  cord,  consequently  that  the  cerebral 
periphery  is  intimately  allied  to  certain  fasciculi  of  the 
spinal  cord  and  the  bulb.1 

The  motor  action  of  the  cortex  cerebri  may  manifest 
itself  in  many  ways  ;  the  action  may  be  normal  or  convul- 
sive, and  some  writers  have  made  interesting  remarks  upon 
that  subject. 

Fritsch  and  Hitzig,3  in  their  work  of  1870,  report  having 
seen  electric  excitations  of  the  cortex  cerebri  provoke 
convulsive  contractions.  These  convulsions  at  first  con- 
fined themselves  to  the  muscles  responding  to  the  cerebral 
region  excited,  then  became  more  general  and  extended  so 
as  at  length  to  become  truly  epileptiform. 

Ferrier  repeated  these  experiments  and  found  that  with 
animals  under  the  influence  of  anaesthetics  there  were  no 
epileptiform  convulsions,  whilst  with  those  not  chloralized 
they  were  easily  provoked.3 

Other  experiments  in  this  field  have  been  made,  especially 
by  Albertoni,4  who  describes  an  epilepto-genetic  zone, 
which  appears  to  be  the  same  as  the  motor-zone  of  Hitzig 
and  Ferrier. 


1  Bouchard  :  Secondary,  degenerations  of  the  spinal  cord,  Arch,  de  méd., 
1866,  p.  443,  t.  i. — Cotard  :  Study  upon  Partial  Atrophy  of  the  Brain,  thèse, 
Paris,  1868,  obs.  iv. — Charcot:  Localizations  in  Diseases  of  the  Brain,  1875. 
Lépin  :   De  la  Localisation  dans  les  maladies  cérébrales,  thèse  d'agrégation, 

1875,  p.  53. — Pitres  :  Soc.  de  Biol.,  21st  Oct.,  1876.— MacDonnel  :  Dub.  Jour. 
Med.  Se,  Nov.,  1377,  p.  451. — MacDonnel  :  Brit.  Med.  Jour.,  14th  July,  1877, 
p.  49. — Vulpian  :  Destruction  of  the  Sigmoid  Gyrus  of  a  Dog,  Arch,  de  phys., 

1876.  s  Loc.  cit.,  p.  317.  3  Loc.  cit.,  p.  208. 

4  Rendiconto  di  esperienze  fatte  nello  gabinetto  di  Sienna,  1876,  2d  semes- 
tre. 


ç6  CEREBRAL   CONVOLUTIONS. 

Franck  and  Pitres  have  made  experiments  upon  cortical 
epilepsy,  and  it  is  through  their  kindness  that  I  am  able  to 
reproduce  here  some  of  their  tracings  (figs.  17,  18). 

It  will  be  seen  that  excitation  of  the  intact  cortical  zone 
produces  phenomena  quite  different  from  those  resulting 
from  excitation  of  the  subjacent  white  fasciculi.  From  the 
first  there  is  a  primary  tetanus  provoked  by  the  direct 
excitation,  but  this  is  followed  by  a  very  remarkable 
secondary  tetanus,  which  is  entirely  absent  in  excitation  of 
the  white  fasciculi.  The  physiological  interest  of  that 
experiment  is  easy  to  comprehend. 

According  to  Franck  and  Pitres,  the  centre  of  the  gray 
substance  which  appears  to  be  the  point  of  departure  may 
be  removed  during  the  provoked  epileptic  attack,  and 
nevertheless  the  paroxysm  will  continue  ;  precisely  as  if, 
immediately  after  transmitting  a  telegraphic  dispatch,  the 
first  end  of  the  wire  were  to  be  cut  ;  that  cutting  would 
not  destroy  the  dispatch  which  had  gone  on  its  way. 

From  the  observations  of  these  authors  it  may  be  con- 
cluded that  cortical  epilepsy  results  from  the  accumulation 
of  excitations  in  the  gray  substance,  which  excite  in  the 
way  of  successive  discharges. 

In  experiments  mutually  conducted  by  Bochefontaine 
and  Viel,  and  recited  in  a  well-written  work  by  the  latter,1 
Viel  has  succeeded  in  producing  epileptic  attacks  by 
another  process. 

Injection  of  nitrate  of  silver  between  the  dura  mater 
and  the  brain  produces  menigo-encephalitis  accompanied 
by  convulsions.  "At  the  onset,'"  says  Viel,  "  there  are  only 
varied  phenomena  of  ataxia.  There  is  an  uncertainty  in  the 
movements  of  the  limbs,  or  of  a  single  limb  on  the  side  opposite 
the  lesion  .  .  .  when  inflammation  supervenes,  the  attacks 
become  clearly  epileptiform,  with  dilated  pupils,  striking 
togetlier  of  the  teeth,  excessive  salivation,  a  tonic  and  a  clonic 
period." 

1  Symptomatologie    de  la    méningo-encéphalite. — Thèse    inaugurale,   Paris, 
1878. 


FUNCTIONS   OF  THE   CONVOLUTIONS. 


97 


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98  CEREBRAL   CONVOLUTIONS. 

Convulsions,  then,  may  be  provoked  by  excitation  of  the 
cortex  cerebri  ;  but  it  does  not  appear  that  the  cause  of 
convulsions  (electric),  studied  by  Hitzig  and  Ferrier,  is  at 
all  analogous  to  the  cause  of  the  convulsions  (inflammatory) 
observed  by  Viel. 

From  the  electricity  there  is  at  first  a  violent  excitation 
of  the  sensibility,  if  not  of  conscious,  at  least  of  reflex  sen- 
sibility. Known  facts  demonstrate  that  excitation  of 
the  convolutions  which  surround  the  sigmoid  gyrus  act 
with  extreme  energy  upon  the  ganglionic  centres  of  the 
brain  (opto-striated  bodies).  It  is  possible  that  such  exci- 
tation cumulates  in  the  cerebral  centres,  and  that  these 
centres  thus  surcharged  send  successive  discharges  to  the 
muscles.  These  are,  of  course,  words  which  ill-cover  our 
ignorance  of  the  phenomenon. 

In  the  experimental  meningitis  of  Viel,  inflammation 
replaced  electric  excitation,  that  is,  substituted  for  the 
physical  excitants  one  much  more  powerful.  It  is  indeed 
the  physiological  excitant  par  excellence — inflammation — 
which  so  readily  produces  hyperkinesia  and  hyperesthesia. 

The  result,  in  fact,  is  the  same,  and  the  phenomena,  in 
foundation,  are  identical.  Exaggerated  excitation  of  the 
cerebral  periphery  produces  convulsions,  at  first  limited  to 
a  group  of  muscles,  then  to  one  side  (the  opposite)  of  the 
body,  and  which  may,  extending,  involve  all  the  muscles 
of  the  body.  Is  not  this  a  very  curious  similarity  to  that 
which  is  observed  in  the  study  of  reflex  actions  in  the 
frog?  In  proportion  to  the  increase  of  the  excitant,  the 
reflexes,  which  at  first  are  localized,  extend  and  become 
more  and  more  general. 

Medical  practitioners  have  gathered  important  facts, 
which  in  a  most  formal  manner  confirm  the  results  obtained 
by  physiologists.  Thus,  more  than  twelve  years  ago, 
Hughlings   Jackson1    announced   that    convulsive    move- 

1  His  scattered  memoirs  have  been  gathered  into  a  book  :  Clinical  and  Patho- 
logical Researches  on  the  Nervous  System. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  99 

ments  of  one  side  of  the  body  depended  upon  a  cortical 
irritation  on  the  opposite  side. 

That  form  of  epilepsy  limited  to  one  side  of  the  body, 
or  to  one  limb,  or  to  the  face,  that  kind  of  epilepsy  which 
Charcot  perhaps  rightly  calls  Jacksonian,  has  been  treated 
of  in  a  remarkable  work  by  Landouzy.1  It  is  now  known 
that  a  lesion  of  the  cortex  cerebri  may  produce  either 
paralysis  or  convulsion  (akinesie,  hyperkinesia),  according"  as 
the  lesion  is  destructive  or  irritative.  The  convulsive 
centres  coincide  absolutely  with  the  motor-centres,  so 
that  the  two  series  of  events  are  completed  and  confirmed 
by  each  other.  In  conclusion,  I  will  observe  that,  besides 
convulsions,  there  is  another  modality  of  motor  innerva- 
tion—contraction. By  an  intense  and  profound  excitant 
at  the  surface  of  the  hemispheres,  Ferrier  has  been  able 
to  produce  contractions.  In  essence,  however,  the  phe- 
nomenon is  not  different.  Using  the  comparison  already 
employed,  the  motor  discharge,  in  place  of  being  inter- 
rupted (clonic  epilepsy),  may  be  continuous  (tonic  contrac- 
tion). 

C.   ACTION    OF    THE    CONVOLUTIONS     UPON    THE     MUSCLES 
OF   ORGANIC    LIFE. 

The  action  of  the  convolutions  upon  the  muscles  of 
organic  life  was  first  studied  by  two  of  Vulpian's  pupils, 
Bochefontaine  and  Lépine."  One  year  previous,  Schiif 
thought  that  he  observed  accelerated  action  of  the  heart 
without  change  of  blood-pressure.3  At  the  same  date 
Kiilz  4  maintained  that  the  encephalic  centres  had  no  action 
upon  the  saliva,  so  that  the  claims  of  Bochefontaine  and 

1  Convulsions  et  paralysies  liées  aux  meningoencephalites.  Thèse  inaug., 
Paris,  1876. 

2  Bull,  de  la  Soc.  de  Biol.,  5  juin  1875,  pp.  230-257. — Bochefontaine:  Etude 
expérimentale  de  l'influence  exercée  par  la  faradisation  de  l'écorce  grise  sur 
quelques  muscles  de  la  vie  organique.— Arch,  de  phys.,  1876,  p.  140. 

3  Arch,  fiir  experim.  Path.,  1874,  15th  Dec,  p.  178. 
*Centralbl.  fiir  med.  Wissens.,  juin,  1S75. 


100  CEREBRAL   CONVOLUTIONS. 

Lépine  to  priority  in  this  important  discovery  are  beyond 
dispute.  It  should  be  observed,  however,  that  Danilewski, 
in  a  communication  to  La  Société  de  medicine  de  Charkow, 
Nov.,  1874,  remarked  that  excitation  of  the  cortex  cerebri 
produced  a  slight  increase  of  blood-tension,  with  slowing 
of  the  pulse  ;  but  the  issue  of  his  memoir  is  subsequent  to 
the  communication  from  Bochefontaine  and  Lépine.1 

If  a  dog  be  curarized  so  as  to  paralyze  voluntary  move- 
ments, and  yet  retain  organic  life,  and  then  the  encephalon 
be  laid  bare,  it  will  be  seen  that  excitation  of  the  gyrus 
will  at  once  cause  blood  to  appear  in  various  spots  on  the 
wound.  Hemorrhages  which  had  ceased  readily  recom- 
mence ;  there  seems  to  be  a  considerable  increase  of  arte- 
rial pressure. 

This  increased  pressure  is  general  and  can  be  at  once 
observed  by  adjusting  a  manomètre  to  the  carotid.  The 
pressure  augments  very  rapidly,  and  is  often  sufficient  to 
expel  a  coagulum  obstructing  the  glass  canal  placed  in  the 
artery.  This  excess  of  tension  is  also  sometimes  mani- 
fested by  the  increased  volume  of  the  brain,  so  that  it  pro- 
trudes through  the  skull  as  a  cerebral  hernia,  an  unfor- 
tunate circumstance  for  the  experimental  enterprise.2 

Differences  of  pressure  may  be  easily  detected  with  the 
sphygmoscope,  but  it  does  not  indicate  the  absolute  pres- 
sure, and  it  is  less  sensitive  than  the  kymographion.  In 
the  tracings  collected  by  Bochefontaine  it  can  be  seen  how 
marked  the  line  of  pressure  is. 

We  here  give  the  tracings  from  an  experiment  made,  in 
company  with  Bochefontaine,  in  Vulpian's  laboratory,  upon 
curarized  dogs,  where  the  electric  excitation  and  the 
arterial  pressure  in  the  carotid  were  inscribed  simultane- 
ously. 

The  principal  results  from  the  experiment,  as  may  be 
seen  from  the  tracing,  are  as  follows  : 

1  Experimentelle  Beitràge  zur  Physiologie  des  Gehirns. — Arch,  de  Pfliiger,  t. 
xi.,  1875,  p.  128. 

2  Bochefontaine,  loc.  cit.,  p.  142. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  IOI 

A.  Electric  excitation,  though  brief,  produces  a  con- 
siderable increase  of  blood-pressure  which  follows  some- 
what slowly,  augmenting  and  persisting,  even  long  after 
cessation  of  excitation. 

B.  There  is  a  notable  change  in  the  cardiac  rhythm  ;  it 
at  first  becomes  very  frequent,  afterwards  much  slower. 

I  will  observe,  moreover  : 

i st.  These  results  arise  from  excitation  of  the  anterior 
portion  of  the  sigmoid  gyrus. 

2d.  Although  the  excitation  be  far  from  intense,  the  ani- 
mal becomes  quickly  exhausted. 

3d.  When  exhaustion  supervenes  and  the  arterial  pres- 
sure is  lowered,  electric  excitation,  even  though  powerful, 
has  scarcely  any  effect. 

Other  experiments  have  shown  to  Bochefontaine  : 

1  st.  That  sometimes  slowing  of  the  pulse  is  replaced  by 
cardiac  acceleration,  the  cause  of  which  is  as  yet  unex- 
plained. 

2d.  That  if  the  pneumogastrics  have  been  cut,  there  is 
always,  after  cortical  excitation,  lowering  of  pressure  and 
slowing  of  pulse. 

3d.  That  excitation  of  the  sigmoid  gyrus  may  be  com- 
pared to  excitation  of  the  sciatic,  which  raises  the  arterial 
tension  and  slows  the  pulse. 

To  this  Danilewski  has  added  an  important  fact,  which 
is,  that  direct  excitation  of  either  the  optic  thalamus  or  the 
corpus  striatum  (except  perhaps  the  caudated  ganglion» 
does  not  produce  a  like  elevation  of  pressure  ;  therefore, 
these  effects  are  not  due  to  diffusion  of  currents,  but  result 
from  the  excitation  itself,  either  of  the  gray  peripheric  sub- 
stance or  of  the  white  substance  beneath. 

Couty's  method  has  led  him  by  an  entirely  different  road 
to  analogous  results. 

First,  he  very  justly  excludes  the  results  of  older  authors 
who  tied  the  carotids  and  vertebrals  ;  for  that  ligation 
produces  not  alone  anaemia  of  single  convolutions,  but  of 
the  entire  mass  of  the  encephalon. 


102  CEREBRAL   CONVOLUTIONS. 

Anaemia  of  the  convolutions,  produced  by  injection  of 
pulverized  substances  into  the  carotids,  first  acts  as  an 
excitation  to  the  convolutions.  Indeed,  all  nerve-anaemia, 
before  destroying,  produces  hyperkinesia  of  the  nerve 
function.  Now  this  intense  excitation  from  anaemia  does 
not  increase  cardiac  tension,  it  slows  the  heart. 

Continuing  his  experiments,  Couty  '  has  injected  lyco- 
podium  into  the  carotids  of  curarized  dogs  in  which  the 
vagi  were  cut.  Under  these  circumstances  he  has  ob- 
served both  cardiac  acceleration  and  increase  of  arterial 
pressure.  Bochefontaine  has  also  found  cardiac  accelera- 
tion in  dogs  after  the  pneumogastric  nerves  were  cut  ;  it 
may  therefore  be  admitted  that,  in  the  absence  or  destruc- 
tion of  the  inhibitory  nerves  of  the  heart,  encephalic  exci- 
tation produces  acceleration  of  the  heart's  action. 

Respecting  accrued  arterial  tension,  I  think  it  has  not 
the  value  given  to  it  by  Couty,  for  Bochefontaine  has  seen 
excitation  of  the  encephalon  (in  dogs  deprived  of  the  pneu- 
mogastrics)  lower  the  pressure,  and  Couty  does  not  suf- 
ficiently take  into  account2  the  arterial  obstruction  which 
evidently  increases  the  blood-pressure  :  this,  it  seems  to  me, 
may  solve  the  want  of  accord  between  the  results  of  the 
two  methods,  when  excitation  is  succeeded  by  paralysis  of 
the  cortex  cerebri,  the  heart's  action  increases  and  tension 
diminishes  ;  later  on,  the  phenomena  become  complicated 
with  spinal  anaemia,  this  we  do  not  enter  into  here. 

This  blood-pressure  seems  to  arise  partly  from  contrac- 
tion of  the  peripheric  arterioles  and  partly  from  excitation 
of  the  pneumogastric,  which  slow  the  heart  and  elevate 
the  pressure.  Excitation  of  the  gyrus,  however,  produces 
other  phenomena  which  I  will  hastily  state  according  to 
the  memoir  of  Bochefontaine. 

In  exciting  points  I,  2,  3,  4  of  Ferrier,  a  considerable 
hypersecretion  of  the  submaxillary  glands  may  be  noticed 
and  which  can  very  well  be  compared  to  that  produced  by 

1  Loc.  cit.,  p.  711.  2  Loc.  cit.,  708. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  103 

lingual  excitation.  Vulpian  in  his  course  has  several  times 
repeated  this  experiment  with  very  clear  results.  When 
the  hemisphere  is  not  excited,  there  is  no  flow,  but  when 
the  gyrus  is  electrized  saliva  escapes  from  the  canula 
placed  in  the  ducts  of  Wharton.  The  action  is  both  direct 
and  crossed. 

Hypersecretion  of  saliva  has  also  been  obtained  from 
points  11,  15,  10,  and  17. 

Movements  have  been  observed,  too,  in  the  pupil,  the 
small  and  large  intestines,  the  Fallopian  tubes,  the  spleen, 
the  bladder,  and  a  most  abundant  secretion  of  bile  or  of 
pancreatic  juice  has  been  induced.  Upon  these  points  I 
refer  to  Bochefontaine's  work. 

But  one  thing  is  necessary  to  remark,  which  is,  that  all 
these  centres  of  movements,  arterial  or  otherwise,  are  lo- 
cated in  the  same  points  from  which  motion  of  the  limbs 
is  provoked  ;  that  is,  about  the  crucial  sulcus. 

The  electric  excitation  must  not  extend  to  the  dura  ma- 
ter ;  for,  as  observed  by  Danilewski  and  Bochefontaine, 
electric  or  even  mechanical  excitation  of  that  membrane 
provokes,  by  reflex  action,  salivary  secretion,  contraction 
of  the  iris,  etc. 

Electrization  of  the  sigmoid  acts  peculiarly  upon  respira- 
tion ;  it  is  not  correct  to  say  that  it  accelerates  it.  At  first, 
there  is  an  irregularity  and  a  certain  acceleration,  then  a 
pause,  which  often  continues  for  half  a  minute. 

I  have  seen  this  verified  upon  a  cat  profoundly  chloral- 
ized,  and  have  noted  some  interesting  phenomena.  When 
all  other  movements  were  suppressed,  the  action  of  the 
bulb  could  be  arrested  by  excitation  of  the  brain.  In  one 
case,  the  arrest  of  respiration  was  so  prolonged  that  death 
would  probably  have  ensued,  had  the  thorax  and  body  of 
the  animal  not  been  vigorously  electrized.  This  agrees 
with  Vulpian's  observation  upon  profoundly  chloralized 
dogs  ;  a  violent  peripheric  excitation  easily  killed  by  sus- 
pended respiration,  or  by  syncope. 

That   reflex   arrest   of   respiration  results  also,  though 


I04  CEREBRAL   CONVOLUTIONS. 

with  greater  difficulty,  from  electrization  of  the  sciatic 
nerve. 

Be  it  as  it  may,  the  respiratory  phenomena,  observed 
in  chloralized  animals,  entirely  resemble  that  which  Franck 
has  noticed  in  rabbits  upon  excitation  of  the  sensorial 
nerves  of  the  face.1 

Brown-Séquard  has  studied  some  of  the  phenomena  to 
which  excitation  or  destruction  of  the  cortex  cerebri  give 
rise.-  I  have  before  said  that  the  cerebral  periphery  was 
not  insensible  to  excitation  ;  that  in  burning  the  surface  of 
the  convolutions  with  a  hot  iron,  certain  immediate  phe- 
nomena could  be  observed  ;  congestion  of  the  conjunctiva, 
closing  of  the  eyelids,  contraction  of  the  pupil  upon  the 
side  of  the  lesion. 

For  that  eminent  physiologist,  these  effects  are  identical 
with  those  obtained  by  section  of  the  great  cervical  sym- 
pathetic. The  degree  of  congestion  appears,  then,  to  be  in 
proportion  to  the  intensity  of  the  excitation,  and  the  ex- 
tent of  the  cerebral  surface  cauterized.  Brown-Séquard 
connects  these  facts  with  the  phenomena  of  arrest,  which 
he  has  elsewhere  so  well  observed. 

Similar  facts,  relating  to  the  action  of  the  Rolandic  con- 
volutions upon  temperature,  have  been  noted  by  other 
writers,  by  Heifler,3  and  especially  by  Eulenburg  and 
Landois.4  These  authors  state  that  excitation  of  the  parie- 
tal convolutions  produces  a  decrease  of  temperature  ; 
whereas  a  destruction,  by  abrasion  or  liquid  caustics, 
causes  a  rise  of  temperature. 

The  facts  of  Eulenburg  and  Landois  are  unfortunately 
very  open  to  objection;  and  several,  particularly  Vulpian5 
and  Kussner,0  have  called  them  in  question.     Hitzig,  cited 


1  Comptes  rendus  du  laboratoire  de  M.  Marey,  1876,  p.  221. 

2  Arch,  de  physiol.,  1875,  p.  854.  3Wien.  Med.  Jahresber.,  1875,  p.  59. 

4  Centralbl.  fiir  med.  Wiss.,  1876,  p.  260,  et  Virchow's  Arch.,  1876,  t.  xviii. 

5  Arch,  de  phys.,  ioc.  cit. 

6  Ueber  vasomotorische    Centren    in   der   Grosshirnrinde   des  Kaninchens. 
Aich.  fiir  Psychiatrie,  p.  432,  1878,  t.  viii. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  105 

by  Kussner,  also  notes  the  absence  of  well-defined  vaso- 
motor phenomena. 

It  seems,  however,  that  a  vaso-motor  and  thermal  action, 
as  yet  little  understood,  is  exercised  by  certain  parts  of 
the  cortex  cerebri  upon  the  tissues,  as  exhibited  in  a  dila- 
tation of  the  vessels  (paralysis)  and  a  contraction  of  them 
(excitation). 

It  is  probable  that  the  facts  of  experimental  and  clinical 
observations,  following  provoked  or  spontaneous  cortical 
lesions,  are  due  to  this  vaso-motor  action.  There  may 
follow  congestions  of  the  lungs,  stomach,  intestines,  etc. 
Of  those  dying  with  lesions  of  the  brain,  Ollivier  has  re- 
ported cases  of  subplural  ecchymoses,  pulmonary  hemor- 
rhages, and  renal  congestions.1  Under  the  same  conditions, 
congestion  of  the  liver,  glycosuria,  polyuria,  and  albumi- 
nuria, etc.,  have  been  observed. 

These  lesions  and  functional  troubles  appear  to  excite 
vaso-motor  modifications  of  which  the  point  of  departure 
would  be  in  the  cortex  cerebri.  Lesions  of  the  cortex 
seem  to  induce  the  vaso-motor  disturbances  daily  noticed 
in  clinic  as  a  sequence  of  cerebral  affections.  We  allude 
to  those  cedemas,  erythemas,  cutaneous  congestions,  often 
eventuating  in  acute  illness,  phases  which  rapidly  super- 
vene upon  the  paralyzed  side.  To  a  certain  degree  they 
depend  upon  the  same  cause  as  do  rise  of  temperature 
and  diminution  of  tension  in  the  vessels  of  the  paralyzed 
side. 

All  these  trophic  troubles  are  acute  in  advent.  There 
are  other  disturbances  which  appear  later  and  which, 
physiologically,  are  o*f  great  importance  :  I  refer  to  secon- 
dary lesions  which,  proceeding  from  the  cortical  lesion,  go 
in  direct  line  by  way  of  the  peduncle  and  protuberance  to 
the  lateral  medullary  column  on  the  opposite  side  of  the 
spinal  cord.  Secondary  degenerations,  true  descending 
scleroses,  may  in  all  respects  be  compared  to  lesions  pro- 

1  Ollivier,  Bull,  de  la  Soc.  de  Biol.,  4th  série,  p.  245.  Modifications  de  la 
secretion  urinaire  après  l'hemorrhagie  cérébrale.     Gaz.  heb.,  1875,  Obs.  I. 


Io6  CEREBRAL   CONVOLUTIONS. 

duced  in  the  peripheric  end  of  a  nerve  separated  from  its 
trophic  centre.  Thus  there  is  authority  to  consider  the 
convolutions  as  veritable  trophic  centres  of  the  nerve-fas- 
ciculi which  leave  them. 

Autopsies  have  demonstrated  that  descending  scleroses 
may  result  from  lesions  belonging  exclusively  to  the  cor- 
tex, the  central  ganglia  being  absolutely  sound.1  These 
scleroses  are  found  not  alone  in  man.  Seven  months  after 
destroying  the  sigmoid  gyrus  in  a  dog,  encephalitis  having 
followed,  Vulpian a  observed  a  descending  atrophy  of  the 
peduncle,  isthmus,  and  the  spinal  cord. 

It  is  under  these  circumstances  that  in  the  limbs  opposite 
to  the  side  of  cerebral  lesion  are  seen  slowly  evolving  tro- 
phic disturbances  ;  scleroses,  retractions  and  contractions, 
muscular  atrophy,  arthritis,  thickening  of  the  subcuta- 
neous cellular  tissue,  etc.  These  troubles  depend  upon 
sclerous  lesions  developed  step  by  step  along  the  spinal 
column,  and  the  results  are  similar  to  those  which  follow 
lesions  of  the  nerves;  that  is,  the  encephalic  alterations 
have  produced  trophic  disturbances  only  by  the  intermedi- 
ation of  secondary  neuroses. 

It  is  also  by  the  intermediation  of  these  neuroses  that 
cortical  lesions  in  infants  entail  arrest  of  development,  mal- 
formations and  atrophies,  so  well  described  in  the  theses  of 
Turner  (1856)  and  Cotard  (1868). 

If  from  these  facts,  the  convolutions  can  be  considered 
as  trophic  centres  of  the  nerves,  as  a  system  of  nerve-pro- 
jection, may  it  not  be  supposed,  a  priori,  that  there  is  a 
relation  between  the  mass  of  cerebral  convolutions  and  the 
peripheric  nervous  system  ? 

The  problem  is  not  yet  solved,  still  there  are  a  certain 
number  of  facts  which  should  be  considered.3 


1  See  Lépine  :  Thèse  d'agrégat.,  1875,  p.  53,  Paris,  1878. — R.  Isartier  : 
Thèse  inaug. — Des  dégénérations  secondaires  de  la  moelle  épinière  consécutive 
aux  lésions  corticales  du  cerveau.  -  Arch,  de  phys. ,  1876,  p.  814. 

3  Luys,  Bull,  de  la  Soc.  Biol.,  8  juillet,  1876. — Féré  :  Bull,  de  la  Soc.  anat., 
mars,  1877.  —  Mossé  :  Bull,  de  la  Soc.  anat.,  février,  1S78,  etc. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  \OJ 

When  a  long  time  has  elapsed  after  the  limbs  have  been 
destroyed  or  amputated,  cerebral  asymmetry  of  the  Rolan- 
dic  convolutions  have  been  observed.  In  one  instance  atro- 
phy was  manifest,  not  only  in  the  convolution,  but  also  in  the 
peduncle  and  bulb,  the  disease-evolution  taking  a  direction 
inverse  to  that  of  descending  sclerose.1 

D.    APHASIA. 

Although  the  study  of  aphasia  introduces  pathology, 
still  it  seems  proper  to  speak  of  it  here,  for  the  reason  that 
physiology  is  the  study  of  functions,  and  one  of  the  func- 
tions of  the  convolutions  in  man  being  language,  it  is  neces- 
sary to  treat  of  it,  even  though  in  a  summary  manner.  To 
tell  the  truth,  our  knowledge  of  aphasia  has,  of  all  the  phy- 
siology of  the  convolutions,  certainly  the  greatest  precision 
and  interest. 

Aphasia  is  not  a  phase  of  motor  paralysis.  The  muscles 
of  the  tongue,  larynx,  and  velum  palati  retain  their  power 
of  contraction,  and  their  functions  are  unaltered.  The 
trouble  is  a  loss  of  ideo-motor  coordination. 

There  is  neither  dementia  nor  paralysis,  the  defect  is 
neither  of  intellection  nor  motion,  but  of  the  bond  which 
unites  the  two,  it  being  the  effort  of  intellection  which  in- 
duces motion.  Meynert  was  the  first  to  describe  the  lesion 
of  aphasia  as  a  fracture  of  the  psycJio-motor  centres.  The 
term  psycho-motor  seems  excellently  applied  to  aphasia  ; 
it  is  not  a  motor  centre,  like  the  ventricle  of  the  gray  sub- 
stance (fourth)  which  is  the  motor-centre  of  respiration, 
nor  is  it  yet  a  psychic  centre,  since  there  is  motor  paralysis  ; 
it  is  a  psyclio-motor  Centre. 

We  say  that  intellection  is  intact  ;  but  it  would  be  erro- 
neous to  consider  the  intelligence  of  aphasiacs  as  unim- 
paired. One  deprived  of  speech  certainly  has  a  lesion  of 
intelligence,  at  least  if  intelligence  embraces  the  totality  of 
intellectual   faculties.     Besides,  all    medical  practitioners 

1  Landouzy,  Bull,  de  la  Soc.anat.,  avril,  1877. 


108  CEREBRAL   CONVOLUTIONS. 

know  that  the  majority  of  aphasiacs  have  childish  ideas, 
weeping,  etc. 

Not  only  is  speech  lost  in  aphasia,  but  all  other  forms  of 
language  (imitation,  drawing,  writing,  reading,  singing) 
are  more  or  less  affected.  Some  aphasiacs  can  express 
neither  negation  nor  affirmation  by  gesture  of  the  head. 

This  is  a  very  important  fact,  for  it  exhibits  an  intellect- 
ual function  absolutely  destroyed  through  lesion  of  a  con- 
volution, as  if  the  convolution  were  the  organ  of  that  func- 
tion. 

Recurring  to  the  question  which  we  have  before  broached 
regarding  the  seat  of  the  lesion,  we  can,  thanks  to  Broca, 
return  very  precise  answers  : 

i  st.  Lesion  of  one  convolution,  and  even  of  a  small  area 
of  its  gray  cortex,  may  of  itself  produce  aphasia. 

2d.  That  convolution  is  the  posterior  part  (generally 
called  foot)  of  the  third  left  frontal  convolution  [convolution 
of  Br  oca). 

3d.  Whenever  the  posterior  portion  of  the  third  left 
frontal  convolution  is  diseased,  there  is  aphasia. 

This  last  law,  however,  is  not  absolute.  There  are 
cases  where  the  lesion  has  been  in  the  island  of  Reil  ; 
others,  in  the  right  hemisphere  ;  in  other  instances 
there  have  been  lesions  of  the  third  left  frontal  without 
aphasia. 

The  exceptions  may  be  classed  thus  : 

a.  Aphasia  without  lesion  of  third  left  frontal. 

a.  With  lesion  of  third  right  frontal. 

b.  Without  lesion  of  third  right  frontal. 

B.  Lesion  of  third  left  frontal  without  aphasia. 

a.  With  lesion  of  third  right  frontal. 

b.  Without  lesion  of  third  right  frontal. 

I  will  not  dwell  upon  facts  which  belong  to  medicine 
rather  than  physiology  ;  it  suffices  to  say  that  all  these  ex- 
ceptions have  been  observed,  but  what  do  they  prove  ? 

If  in  one  hundred  cases  of  the  same  disease,  the  same 
lesion  be  found  in  ninety-nine,  the  exception  being  one,  can 


FUNCTIONS   OF   THE   CONVOLUTIONS.  IO9 

it  be  said  that  there  is  no  relation  as  cause  and  effect  be- 
tween the  lesion  and  the  disease  ? 

If  in  one  hundred  aphasiacs,  ninety-nine  have  the  third 
left  frontal  convolution  destroyed,  would  it  be  justifiable 
to  say  that  this  is  not  the  seat  of  the  faculty  of  articulate 
language  ? 

For  my  part  1  think  not,  and  I  believe  that  the  localiz- 
ing of  language  in  the  foot  of  the  third  left  convolution, 
or  better,  the  convolution  of  Broca,  is  very  firmly  and 
amply  established. 

But  we  must  fully  consider  the  exceptions  :  they  show 
to  us  that  the  convolution  of  Broca  is  not  to  language  that 
which  the  retina  is  to  vision,  or  the  testicle  to  spermato- 
genesis. We  cannot  comprehend  vision  without  a  retina, 
or  spermatogenesis  without  a  testicle,  but  one  can  con- 
ceive that  other  parts  of  a  hemisphere  may  replace  those 
which  generally  preside  over  a  function. 

ft  is  still  easier  to  comprehend  how  the  right  hemisphere 
may  replace  the  left  :  the  same  as  there  may  be  one  left- 
handed  person  for  one  hundred  right-handed  ones,  so  there 
may  also  be  one  individual  out  of  a  hundred  who  speaks 
from  the  right  hemisphere  :  that  would  be  a  left-handed 
speaker,  as  Broca  happily  expresses  it. 

We  have  seen  that  experimental  cortical  paralyses  have 
a  triple  character  ;  they  are  partial,  inconstant,  transitory. 
Such  are  also  the  traits  often  presented  by  aphasia.  Un- 
fortunately, this  most  interesting  history  of  transitory 
aphasias,  based  upon  autopsy,  is  not  yet  complete. 

E.   THEORIES   OF    MOTOR   INNERVATION   OF   THE    CONVOLU- 
TIONS. 

We  have  given  the  facts,  and  we  will  now  see  how  they 
can  be  grouped  so  as  to  establish  a  theory  and  a  system  of 
unity. 

Moreover,  we  will  have  occasion  in  this  chapter  to  men- 
tion other  facts  which  did  not  logically  have  place  amongst 
the  preceding  ones. 


IIO  CEREBRAL   CONVOLUTIONS. 

All  theories  can  be  reduced  to  two  principal  ones. 

A.  There  are  motor-centres  (Hitzig,  Ferrier). 

B.  There  are  no  motor-centres  ;  there  are  but  reflex 
(Schiff),  or  irritative  actions  (Brown-Séquard).  It  will  be 
necessary  also  to  discuss  two  hypotheses  which  may  be 
called  accessories,  for  the  reason  that  they  only  seek  to 
explain  a  part  of  the  phenomena  in  order  to  support  one 
or  the  other  of  the  two  theories,  the  supplemental  hypothe- 
sis and  the  hypothesis  of  paralysis  of  the  muscular  sense. 

First  we  will  examine  the  theory  defended  by  Hitzig 
and  Ferrier,  and  with  some  modifications  by  Carville  and 
Du  ret. 

The  hypothesis  of  motor-centres  rests  upon  two  facts 
which  we  have  already  considered  and  fully  verified. 

i  st.  Excitation  of  strictly-limited  cortical  zones  provokes 
motion  in  certain  determined  groups  of  muscles. 

Respecting  the  exact  limitation  of  motor-zones,  it  has 
been  observed  by  Hitzig,  Rouget,  and  all  other  authors, 
that  it  is  only  necessary  to  change  the  electrodes  some 
millimetres  in  order  to  obtain  a  movement  different  from 
the  preceding  one.  According  to  Bochefontaine,'  when 
a  section  of  the  convolutions  bordering  the  crucial  furrow 
is  examined  with  the  naked  eye,  conical  tufts  of  the  white 
substance  may  be  seen  penetrating  the  gray  cortex,  directed 
towards  the  surface  of  the  brain.  Perhaps  as  different 
ones  of  these  tufts  are  approached,  varied  effects  will  ensue 
upon  the  anterior  or  the  posterior  limbs. 

Exact  limitation  of  movement  to  such  or  such  a  muscu- 
lar group  does  not  prove  the  existence  of  a  veritable 
motor-centre  for  that  muscular  group.  The  excitation  of 
any  selected  sensorial  nerve  provokes,  if  the  excitation  be 
not  too  intense,  a  reflex  motion  in  a  certain  determined 
group  of  muscles.  Will  it  be  said  that  such  sensorial  nerve 
is  the  motor-centre  of  such  muscular  group  ? 

To  determine  the  existence  of  motor-centres  then,  resort 
must  be  had  to  other  proofs. 

1  Bull,  de  la  Soc.  de  Biol.,  23d  Dec,  1S77  ;  Progrès  médical,  1S78,  p.  9. 


FUNCTIONS   OF   THE    CONVOLUTIONS.  Ill 

Pathology  cannot  supply  a  rigorous  proof  of  the  exist- 
ence of  motor-centres  in  the  cortex  cerebri. 

According  to  Charcot,  paralysis  does  not  follow  a 
disease  of  the  gray  substance  alone,  moreover,  there  are 
pathological  facts  '  which  seem  to  prove  that  the  localiza- 
tion of  motor-centres  in  various  regions  of  the  same  con- 
volution, of  the  ascending  frontal  for  example,  cannot  yet 
be  determined  with  sufficient  precision. 

Thus  it  cannot  be  demonstrated  that  the  gray  substance 
is  a  centre. 

The  experiment  which  we  have  before  recited  showed 
that  the  gray  substance  was  very  probably  excitable  by 
electricity.  Now  there  remains  to  be  ascertained  what 
part  electricity  plays  in  the  phenomenon  of  motion. 

Couty  has  made  experiments  which  I  have  already  men- 
tioned ;  I  cannot  enter  into  their  details,  but  he  has  noticed 
that  the  gray  substance  can  be  anaemied  without  producing 
change  in  arterial  tension  :  he  has  concluded  that  electricity 
acts  by  the  white  substance  and  not  by  the  gray.  This 
conclusion  seems  to  me  rather  hypothetical,  all  the  more  so 
that,  according  to  Couty  himself,-  anaemia  of  the  gray  sub- 
stance of  the  brain  produces  a  constant  and  considerable 
cardiac  slowing.  It  is,  then,  very  probable  that  the  gray 
cortical  substance  acts  upon  the  heart,  as  seems  proven 
also  by  the  influence  of  emotions  and  sentiments  upon  the 
rhythm  of  the  heart.3 

As  respects  the  non-excitability  of  the  gray  substance 
by  electricity,  we  have  already  dwelt  upon  the  subject 
sufficiently  to  render  a  return  to  it  unecessary.  The  very 
indirect  method  of  Gouty  does  not  seem  to  have  disturbed 
the  direct  and  positive  proofs  of  which  we  have  spoken. 

Our  experiments,  as  well  as  those  of  Franck  and  Pitres 

1  See  la  thèse  de  M.  Mallebay,  des  paralysies  partielles  d'origine  corticale. 
Paris,  1878,  No.  2S6. 

2  Loc.  cit.,  p.  724. 

3  Voyez  la  belle  leçon  de  CI.  Bernard  sur  ce  sujet  :  Leç.  sur  les  tissues  vivants, 
P-425- 


112  CEREBRAL   CONVOLUTIONS. 

demonstrate  that  the  gray  substance  is  excitable,  but  they 
do  not  prove  a  veritable  localization  of  motor-centres  in  the 
gray  substance. 

We  come  to  the  second  fact  urged  by  the  partisans  of 
motor-centres. 

2d.  Removal  of  those  parts  of  the  gray  cortex  which  are 
considered  as  motor-centres  is  followed  by  paralysis. 

That  paralysis  does  follow,  however,  has  been  contested, 
and  eminent  physiologists,  Schiff,  Nothnagel,  Hermann, 
Goltz,  etc.,  have  attributed  the  phenomena  observed  to 
quite  another  cause. 

Without  fully  entering  the  discussion,  we  will  notice  some 
of  its  particulars. 

Schiff1  says  that  it  is  the  surety  and  precision,  and  not 
the  energy  of  movement  which  is  affected.  "  Often"  says 
Scliiff,  "  we  have  publicly  exhibited two  dogs,  one  deprived  of  the 
cortical  centre,  the  other  with  both  posterior  columns  of  the  spine 
in  the  upper  dorsal  region  destroyed,  and  no  difference  could  be 
found  in  their  movements." 

Ferrier's  objection,2  that  loss  of  the  muscular  sense  does 
not  exist  without  an  affection  of  other  forms  of  tactile  sensi- 
bility, is  of  little  significance.  On  the  contrary,  he  rightly 
says  that  pathological  observations  prove  that  cortical 
lesions  produce  a  true  paralysis,  and  not  a  loss  of  muscular 
sense,  and  this  objection  carries  great  force  ;  we  will  pres- 
ently examine  it. 

Ferrier  also  says3  that  that  which  he  calls  tactile  sensi- 
bility, by  others  termed  muscular  sensibility,  is  affected 
when  the  lobule  hippocampi  is  destroyed,4  but  that  is 
debatable,  especially  as  other  observers  have  detected  mus- 
cular sensibility  from  other  regions.  Hitzig,5  in  particu- 
lar, thinks  that  destruction  of  anterior  portion  of  the  sig- 

1  Arch,  fiir  experim.  Pathol,  und  Pharmac,  t.  iii.,  1874,  p.  170. 
-  Loc.  cit.,  p.  350.  3  Luc.  cit.,  p.  285. 

4Neue  Untersuchungen,  1S74,  Arch,  fiir  Anat.,  p.  415  et  suiv. 
5  Pfliiger's  Arch,  ueber  die  Verrichtungen  des  Grosshirns,  t.  xiii.,  p.  1,  1876, 
t.  xiv.,  p.  412,  1877. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  II3 

moid  gyrus  destroys  muscular  sensibity  of  the  opposite 
side,  and  he  concludes  : — the  convolution  upon  which  mus- 
cular sensibility  depends  is  not  directly  excited  by  elec- 
tricity and  is  not  a  motor-centre. 

We  call  attention  to,  as  being  very  interesting,  the 
recent  experiments  of  Goltz  and  Gergens  to  which  Hitzig1 
has  as  yet  but  partially  replied.  Goltz  considers  that 
which  Hitzig  calls  defect  of  voluntary  energy  {Defect  der 
Willenscncrgié)  as  only  a  trouble  of  muscular  sensibility, 
and  a  propos  gives  the  following  experiment  : — With  a  dog, 
habituated  to  giving  equally  either  paw,  the  surface  of  the 
left  convolutions  was  removed.  For  one  month  she  was 
not  able  to  give  the  right  paw  ;  for  two  months  she  made 
efforts  to  do  so,  but  only  sometimes  succeeded,  in  a  very 
irregular  manner  ;  finally,  at  the  end  of  four  months  she 
became  able  to  effect  it  in  a  tolerably  regular  manner, 
though  with  more  hesitation  than  before  the  operation. 
A  new  operation  upon  the  same  side  destroyed  anew  the 
power  of  voluntary  movement.  That  would  seem  to  prove 
that,  if  the  first  operation  had  destroyed  voluntary  motion, 
it  was  not  as  a  result  of  a  removal  of  the  gray  matter  or  of 
the  whole  substance,  but  a  kind  of  irritation  paralyzing 
muscular  movements. 

Goltz  gives  another  curious  experiment.  He  made 
a  continuous  pressure,  with  nippers,  to  the  great  toes  of 
a  dog,  and  observed  that  the  operation,  as  concerned 
paralysis  and  motor  disturbances,  was  the  same  that 
occurred  with  a  dog  in  which  the  opposing  hemisphere 
had  been  destroyed.2  Tripier3  has  seen  cases  of  the  same 
kind.  With  dogs'  recovered  from  a  cortical  paralysis, 
a  hypodermic  injection  of  morphine,  a  free  bleeding,  or 
an  epileptic  crisis  brings  back  the  paralysis.  Analogous 
facts  are  observed  in  man. 

The  conclusion  that  this  is  an  exhibition  of  irritation 
(paralysis   by   arrest,  Hemmungsersckeinungen)   is   perhaps 

1  Arch,  fur  Anat.  und  Physiol.,  1876,  p.  692. 

2  Loc.  cit.,  1877,  p.  442.  3  Revue  Mensuelle,  1877,  p.  9. 


I  14  CEREBRAL   CONVOLUTIONS. 

hypothetical.  It  is,  however,  worthy  of  notice,  for  it 
again  shows  the  great  resemblance  that  exists  between 
that  which  is  called  the  motor-zone  of  the  convolutions 
and  the  sensorial  nerves  of  the  periphery. 

It  is  a  similar  theory  that  Brown-Séquard  has  with  well- 
known  talent  defended,  and  for  which  he  has  adduced  an 
imposing  array  of  data. 

The  theory  of  paralyses  by  irritation  is,  however,  still 
hypothetical,  especially  as  the  effects  of  excitation  are 
rarely  paralyses,  and  as  by  experimentally  irritating  the 
surface  of  the  brain,  partial  epilepsies  and  contractions 
can,  as  before  said,  be  produced. 

But  the  fact  that  a  pathological  lesion  of  the  hemi- 
sphere produces  paralyses  and  not  a  loss  of  muscular  sense,, 
should  render  us  very  reserved  respecting  the  theory  of 
Schiff,  Nothnagel,  and  Goltz,  for  here  we  are  forced  to 
recognize  a  real  paralysis  with  loss  of  voluntary  motion. 

As  concerns  the  brain,  the  comparison  between  man 
and  animal  is  not  so  close  and  formal  as  it  is  respecting 
many  other  functions,  and  of  this  the  best  proof  is  that 
cortical  paralyses  in  man  are  permanent,  while  with  dogs 
they  are  transitory. 

The  fact  that  paralyzed  animals  afterwards  recover  has 
been  carefully  noticed  by  Carville  and  Duret.1 

These  observers  also  state  that,  if  after  a  lesion  of  the  sig- 
moid gyrus  (on  the  right,  for  example),  the  animal  becom- 
ing paralyzed  and  then  recovering,  the  removal  of  the  left 
gyrus  be  effected,  it  will  not  result  in  a  paralysis  of  both 
sides,  consequently  it  cannot  be  admitted  that  a  certain 
part  of  one  hemisphere  supplements  or  assumes  the  func- 
tions of  the  corresponding  part  of  the  other  hemisphere." 

This  brings  us  to  the  theory  of  supplementation,  the 
stumbling-block  of  the  theory  of  motor-centres. 

To  judge  of  this  theory,  we  must  include  a  considera- 
tion of  two  diverse  supplemental  localities  ;  first,  a  supple- 

1  See  Exp.  v.,  p.  434  of  the  mémoire  already  cited,  also  p.  450  et  suivante. 

2  See  inaugural  thesis  of  Parant  :   Des  Suppléances  Cérébrales,  Paris,  1877. 


FUNCTIONS    OF   THE   CONVOLUTIONS.  I  15 

ment  furnished  by  the  opposite  hemisphere,  and,  second, 
that  furnished  by  other  parts  of  the  same  hemisphere. 

1  st.  It  is  very  easy  to  understand  that  the  right  hemi- 
phere  might,  to  a  certain  degree,  supplement  the  left  and 
vice  versa,  the  two  being  similar  and  symmetrical.  For 
aphasia,  this  has  been  admitted.  One  may  also  reason  to 
himself  that  a  dog  with  the  left  so-called  psycho-motor 
centre  destroyed  cannot  raise  the  right  foot,  but  can  walk 
equally  well  with  both  feet,  the  act  of  walking  being  a 
reflex  one,  provoked  by  contact  with  the  ground.  To 
explain  this  fact,  which  may  seem  somewhat  obscure,  let 
us  compare  the  psycho-motor  centre  of  the  retina.  Exci- 
tation of  the  retina  produces  reflex  action  of  the  iris.  For 
example,  when  the  right  retina  is  destroyed,  the  right  iris 
will  no  longer  contract,  but  in  this  case,  however,  if  light 
be  suddenly  thrown  upon  the  left  retina,  the  right  iris 
will  contract  by  crossed  reflex  action.  These  facts  are 
beyond  dispute,  but  experience  shows  that  for  cortical 
centres,  supplementation  by  the  opposite  side  does  not 
exist,  and  that  voluntary  motion  is  retained  even  after 
ablation  of  the  gyrus  in  both  hemispheres. 

2d.  Supplementation  by  .the  gray  cortex  of  the  same 
side  must  be  admitted  :  and  this  is  precisely  the  supple- 
mentation which  is  most  difficult  to  comprehend. 

If  the  convolution  which  surrounds  the  crucial  furrow 
is  really  the  motor-centre  of  the  legs,  then,  by  removing 
both  right  and  left  convolutions,  all  four  legs  should  be- 
come paralyzed  ;  if  not,  then  it  is  not  a  true  motor-centre. 
A  function  being  given  to  an  organ,  a  removal  of  the  organ 
should  cause  cessation  of  function.  Both  retinas  destroyed, 
sight  is  abolished.  It  would  then  be  necessary  to  admit 
that  there  are  several  organs  for  one  function,  several 
motor-centres  for  each  limb,  which  certainly  is  contrary  to 
probabilitv  and  to  fact. 

So  the  term  supplementation  signifies  nothing,  except 
that  those  who  admit  it  cannot  admit  true  motor-centres. 
In  man,  cortical  paralyses  are  not  transitory,  they  are  per- 


Il6  CEREBRAL   CONVOLUTIONS. 

manent  ;  and,  therefore,  perhaps  a  difference  should  be 
recognized  between  the  encephalon  of  man  and  that  of 
dog. 

To  sum  up  : — the  ablation  of  centres,  called  motor,  proves 
only  one  thing,  which  is,  that  the  conduction  of  will  is  in- 
terrupted ;  the  same  after  section  of  the  sciatic,  the  muscles 
of  the  leg  are  paralyzed  ;  and  still  the  same  after  section 
of  the  white  fasciculi  of  the  cortical  motor-zone,  the  muscles 
in  rapport  with  these  fasciculi  are  paralyzed. 

There  is,  however,  this  difference.  The  conduction  of  the 
will  is  in  this  last  case  interrupted  only  for  a  time,  whereas, 
when  the  nerve  is  cut,  it  is  suppressed  forever. 

This  would  seem  to  indicate  that  cerebral  conduction, 
at  least  in  the  dog,  has  no  absolutely  marked-out  route. 
Vulpian  has  demonstrated  that  in  the  spinal  cord  conduc- 
tion is  carried  on  equally  by  all  parts  of  the  gray  substance. 
It  is  possible  that  the  same  indifference  holds  for  the  brain, 
though  in  less  degree.  There  are  liabitual  roads,  but  no 
compulsory  ones. 

We  will  now  review  the  opinion  of  those  who  regard 
the  motor  actions  of  the  cerebral  hemispheres  as  reflex. 

ist.  Schiff  supposes  the  reflex  power  of  the  gray  sub- 
stance to  be  annihilated  by  anaesthetics  (chloral,  chloroform, 
ether),  without  their  modifying  the  conducting  power  of 
the  white  substance.  Consequently,  whenever  anaesthetics 
suppress  a  nerve-function,  that  nerve-function  must  pro- 
ceed from  the  gray  substance.  Now,  anaesthetics  suppress 
the  functions  of  the  motor  cortex,  not  only  of  the  gray  cor- 
tex, but  also  the  subjacent  white  fasciculi.  These  subja- 
cent white  fasciculi  enter  the  gray  centres  which  the  chloro- 
form has  paralyzed,  and  the  movements  induced  by  elec- 
trization of  the  cortex  are  purely  reflex. 

This  opinion  includes  several  hypotheses,  which  it  would 
be  necessary  to  demonstrate. 

First,  it  is  not  certain  that  in  anaesthesia,  sufficiently 
profound  to  suppress  all  excito-motor  power  of  the  convo- 
lutions, there  is  no  disturbance  in  the  conduction  of  the 


FUNCTIONS   OF   THE   CONVOLUTIONS.  WJ 

white  substance.  On  the  contrary,  it  is  probable  that 
chloroform  and  ether  act  energetically  upon  the  cylinder- 
axes  of  the  white  substance,  and  end  by  killing  them,  as 
they  kill  the  nerve  or  muscle. 

In  the  next  place,  can  there  be  no  conduction  by  the 
gray  portions  of  the  medulla-oblongata  and  bulb,  other 
than  such  as  is  identical  with  reflex  action?  That  conduc- 
tion by  the  central  axis  of  the  spine  is  no  longer  an  hy- 
pothesis. It  has  been  demonstrated  in  all  ways  by  Vul- 
pian,  and  it  is  very  probable  that,  in  the  peduncles  as  in 
the  protuberance,  conduction  is  effected  by  the  gray  parts. 
What  is  there  astonishing,  then,  in  finding  the  conducting 
power  of  these  cells  abolished  by  anaesthetics,  which  kill 
nerve-cells  ? 

Schiff  adds  another  fact  to  fully  demonstrate  that  we 
really  have  to  do  with  reflex  action.  It  is,  that  the  con- 
duction is  very  slow,  and  the  retard  considerable  ;  very 
much  greater  than  with  the  nerves  or  nerve-fibres,  and 
equally  as  slow  as  a  reflex  action. 

2d.  In  proportion  as  the  excitation  is  weak  or  strong, 
the  movements  are  more  or  less  marked,  and  at  the  same 
time  become  more  and  more,  general.1 

This  is  certainly  true;  we  have  at  various  times  ob- 
served it.  By  increasing  the  exciting  current,  movements 
in  both  legs  are  produced.  Is  this  a  phenomenon  of  diffu- 
sion ?     Possibly  ;  but  the  argument  has  no  great  value. 

3d.  The  strongest  argument  favoring  the  hypothesis  of 
reflex  action  is,  that  along  with  movements  in  the  limb, 
there  are  also  movements  in  the  arteries,  the  iris,  the  heart, 
etc.  ;  consequently,  if  would  be  necessary  to  admit  cardio- 
motor,  vaso-motor,  secreto-motor  centres,  etc. 

Vulpian,  in  his  course,  dwells  upon  the  invariable  fact 
that  excitation  of  the  sigmoid  gyrus  is  always  sensible.  Non- 
chloralized,  the  animal  always  struggles  and  utters  cries 
of  pain  :  slightly  choralized,  electric  excitation  of  the  gyrus 

1  Hermann,  Pfliiger's  Arch.,  t.  x.,  p.  77. 


Il8  CEREBRAL   CONVOLUTIONS. 

re-wakens  them  and  a  profound  anaesthesia  is  requisite  in 
order  that  they  shall  manifest  no  sign  of  sensibility.  All 
the  phenomena  of  respiratory  and  cardiac  arrest  are  com- 
plicated with  a  painful  excitation,  and  the  difficulty  is  to 
discriminate  which  belongs  to  sensibility  and  which  to  an 
excito-motor  cause. 

It  may  be  regarded  as  certain  that  surrounding  the  sig- 
moid gyrus  there  are  white  fasciculi  beneath  the  gray 
substance,  the  excitation  of  which  produces  at  the  same 
time  sensation,  visceral  movements,  and  arterial  contrac- 
tions. Have  all  these  white  fasciculi  exact  limits,  and  are 
there  vaso-motor,  secreto-motor  centres,  etc.?  It  is  very 
improbable. 

Some  light  may  be  afforded  towards  a  theory  of  these 
phenomena  from  that  which  transpires  in  the  spinal  cord 
and  its  reflexes.  The  nerves,  after  they  have  left  the 
spine,  divide  into  a  multitude  of  branches,  and  upon  reach- 
ing the  periphery  present  a  very  extended  surface.  The 
peripheric  nerve-terminations  represent  a  vast  surface 
of  dissociation,  the  spinal  cord  a  line  of  condensation. 
Exciting  a  point  of  that  surface,  two  series  of  diverse 
movements  will  result,  first,  a  local  movement  of  the 
muscle  responding  to  the  touched  cutaneous  surface  ; 
second,  a  distant  movement  which  traverses  the  spinal 
cord  to  the  bulb  and  then  is  reflected  to  delicate  and  im- 
pressionable organs,  such  as  the  iris,  the  heart,  the  vaso- 
motors, etc.  ;  these  organs,  indeed,  are  extremely  perfected 
aesthesiometers,  and  the  least  bulbo-medullary  excitation 
provokes  them  to  motion. 

This  being  the  case,  is  not  the  phenomenon  identical 
with  that  resulting  from  excitation  of  the  brain?  There  is, 
first,  excitation  of  the  fasciculi  which  causes  movement  in 
the  muscles  ;  but  as  that  excitation  extends  also  to  the 
bulb,  and  as  the  reflex  centres  of  the  iris,  heart,  and  vessels 
are  extremely  sensitive,  the  iris,  heart,  and  vessels  are 
immediately  influenced  by  that  bulbo-medullary  excitation. 

Now  to  a  certain  degree  we  can  compare  the  apparatus 


FUNCTIONS   OF   THE   CONVOLUTIONS.  119 

of  cutaneous  peripheric  dissociation  to  the  apparatus  of 
peripheric  dissociation  of  the  cortex  cerebri  ;  the  two 
systems  being  in  close  connection  with  the  nerve-axis  of 
the  gray  substance.  The  excitation  of  either  one  of  these 
apparatuses  produces  two  kinds  of  reflexes,  one  limited 
and  localized,  depending  upon  the  region  primitively 
excited  ;  the  other  disseminated,  depending  simply  upon 
the  bulbo-medullary  excitation  which  is  irradiated.  On 
the  one  hand  are  reflexes  of  localization,  on  the  other, 
reflexes  of  diffusion. 

This  comparison,  however,  would  not  seem  to  be  entirely 
exact,  as  pathological  anatomy  has  demonstrated  the  exist- 
ence of  fasciculi  (trophic  or  excito-motor)  which  lead  direct- 
ly from  the  periphery  of  the  convolutions  to  the  spine 
without  entering  the  central  ganglia  and  the  gray  sub- 
stance, the  encephalic  axis. 

It  may  be  conceived  that  in  the  white  Rolandic  fasciculi 
there  are  two  orders  of  fibres  ;  some  going  directly  to  the 
spine  without  entering  the  gray  substance  (these  are  the 
fasciculi  the  existence  of  which  seems  demonstrated  by 
descending  scleroses),  others  are  lost  in  the  central  gray 
substance  of  the  corpora  striata,  the  peduncles,  and  espe- 
cially of  the  protuberance  and  bulb  ;  their  excitation  pro- 
vokes excitation  of  the  bulb,  and  in  this  way  reflex  move- 
ments in  all  the  apparatus  of  organic  life.  It  may  be  asked 
if  all  the  white  motor  fasciculi  go  directly  to  the  muscles, 
if  a  certain  number  of  them  do  not  pass  by  way  of  the  gray 
centres  of  the  spinal  cord. 

All  these  hypotheses  are  interesting,  because  precise 
researches  can  probably  be  instituted  to  confirm  one  or 
another. 

If  we  now  bring  together  these  different  facts  and 
endeavor  to  establish  a  synthesis  by  applying  to  them  the 
acquired  knowledge  of  general  nerve-physiology,  it  will  be 
seen  that  if  certain  parts  of  the  brain  are  excitable  whilst 
others  are  not,  it  arises  from  their  connections.  Faradiza- 
tion produces  sensation  and  pain  when  the  excited  fibres 


120  CEREBRAL   CONVOLUTIONS. 

are  connected  with  the  opto-striated  bodies  and  the  bulb, 
whilst  excitation  of  the  other  white  fibres  of  the  brain  not 
so  connected  gives  no  sensation  or  pain.  It  also  depends 
upon  the  connection  or  non-connection  of  these  fibres  with 
the  spinal  cord  that  there  are  degenerations  in  certain 
regions  and  not  in  others. 

The  apparatus  of  the  convolutions  can  be  assimilated  to 
that  of  the  nerve-periphery.  They  both  are  joined  to  the 
centres  by  convergent,  centripetal  fibres,  but  at  their 
peripheric  commencement  these  fibres  are  so  dissociated 
that  they  can  be  individually  submitted  to  lesion. 

It  seems  that  the  periphery  of  the  convolutions  is  the  seat 
of  complex  actions,  actions  not  understood,  intellection  ;  that 
the  excitation  of  the  will  is  transmitted  from  it  to  the 
ganglionic  centres  by  special  fibres,  and  that  from  a  lesion 
of  these  fibres  paralysis  ensues. 

This  localization,  however,  does  not  exist  equally  with 
all  animals.  Milne  Edwards  has  fully  demonstrated  that 
in  proportion  to  the  ascent  in  the  scale  of  beings,  division 
of  labor  becomes  more  perfected.  Applying  this  knowl- 
edge to  innervation,  we  may  suppose  that  in  the  same 
manner  conduction  becomes  more  and  more  precise.  The 
white  fasciculi  intended  to  transmit  such  movements  form 
more  numerous  and  better  determined  groups.  As  Vul- 
pian  long  ago  said,  and  as  Ferrier  demonstrated  in  his 
experiments,  the  mechanism  of  the  convolutions  becomes 
more  important  and  complex  in  proportion  to  the  rank 
which  the  individual  occupies  in  the  animal  series.  In 
young  animals,  which  are  inferior  beings,  there  is  no  motor 
excitability  of  the  cortex  cerebri.1 

The  convolutions  are  an  apparatus  of  luxury,  an  addition 
superimposed  to  the  essential  vital  system,  being  formed 

1  Soltman,  Centrait),  fur  d.  med.  Wissensch.,  1S75.  14,  p.  209.  I  have  been 
told  by  Bochefontaine  that  he  has  verified  this  important  fact.  In  new-born 
guinea-pigs,  however,  which  are  at  birth  quite  advanced  in  development,  the 
cortex  cerebri  is  excitable.  Tarchanoff  (Gaz.  méd.,  1878,  p.  441),  is  publishing 
a  very  interesting  work  upon  the  development  of  psycho-motor  centres  in 
young  dogs. 


FACTIONS   OF   THE   CONVOLUTIONS.  121 

by  the  substance  which  surrounds  the  central  encephalo- 
medullary  canal. 

As  for  the  facts,  they  can  be  recounted  in  a  few  lines. 

A.  In  the  dog,  cortical  paralyses  are  transitory  ;  with 
the  monkey  they  are  permanent  (Ferrier),  and  as  concerns 
man,  Charcot  has  demonstrated  by  an  imposing  collection 
of  proofs,  that  a  lesion  of  the  hemisphere  without  any 
lesion  of  the  central  ganglia  will  produce  permanent 
paralysis. 

B.  Cortical  lesions  (Rolandic)  never  induce  anaesthesia 
(immediate  or  consecutive)  in  man,  though  they  certainly 
affect  sensation  in  the  dog. 

C.  There  is,  then,  between  the  human  brain  and  that  of 
the  dog  a  notable  difference,  so  that  conclusions  cannot 
be  drawn  from  one  for  the  other,  except  with  great  reserve. 

D.  In  man  there  are  some  exceptions,  very  few  (if  all 
the  doubtful  cases  are  excluded),  still  a  certain  number 
which  are  well  authenticated,  where  profound  and  exten- 
sive lesions  of  one  or  the  other  of  the  Rolandic  convolutions 
have  not  produced  paralysis,  as  also  lesions  of  the  convo- 
lution of  Broca  have  not  resulted  in  aphasia. 

E.  In  the  great  majority  of  cases,  however,  a  cortical 
lesion  produces  sclerosis  of  the  lateral  cords  of  the  medulla 
oblongata,  etc.,  without  having  affected  the  central 
ganglia.  If,  as  is  probable,  the  trophic  (?)  and  the  excito- 
motor  actions  pursue  the  same  tract,  it  may  be  concluded 
that  there  are  white  fasciculi  going  directly  from  the 
Rolandic  zone  to  the  spine  and  muscles  without  passing 
through  the  central  ganglia. 

F.  On  the  other  hand,  it  is  certain  that,  in  the  dog,  any 
excitation  of  the  Rolandic  cortical  zone  not  only  acts 
(directly  ?)  upon  the  muscles,  but  also  upon  sensation, 
arterial  pressure,  salivary  secretion,  the  vaso-motors,  etc. 

G.  In  the  new-born,  the  cortex  cerebri  is  not  excitable, 
still  they  are  capable  of  movement  and  sensation  (uncon- 
scious?). x\fter  abrasion  of  the  sigmoid  gyrus,  new-born 
dogs  suffer  no  paralysis. 


122  CEREBRAL   CONVOLUTIONS. 

H.  Are  there  psycho-motor  centres?  That  is  doubtful 
and  of  very  little  importance.  It  is  a  great  result  for 
united  physiology  and  pathology  to  have  demonstrated 
that  the  psycho-motor  fasciculi  are  more  developed  in 
man  than  in  the  dog. 

I.  i st.  With  most  individuals,  though  not  with  all,  psy- 
cho-motor fasciculi  exist,  well  limited,  and  may  be 
individually  paralyzed,  atrophied,  or  super-excited. 

2d.  This  individualization  of  the  fasciculi  is  imperfect 
in  the  dog,  not  only  as  between  the  various  motor  fasciculi, 
but  also  between  the  cortical  motor  zone  and  the  other 
zones  of  the  brain. 

3d.  The  psycho-motor  apparatus,  comprising  the  cortex 
of  the  convolutions  and  the  conducting  fibres,  is  much  less 
developed  in  animals  than  in  man. 

4th.  It  is  an  apparatus  which  is  slowly  perfected  and 
only  in  very  superior  animals. 

These  conclusions  evidently  are  not  very  satisfying,  but 
they  make  no  pretense  to  a  theory  and  only  serve  to  explain 
how  practitioners  and  physiologists  may  furnish  for  the 
same  problem  solutions  so  apparently  different. 


Sec.  2.  SENSORIAL   FUNCTIONS  OF   THE    CON- 
VOLUTIONS. 

We  have  seen  that  the  motor  parts  of  the  cortex  cerebri 
are  also  the  sensorial  parts.  Vulpian  was  one  of  the  first 
to  dwell  upon  this  very  important  fact.  This  sensibility  is 
that  termed,  general  sensibility. 

But  in  different  parts  of  the  cerebral  peripheny  there  are 
still  other  regions  reserved  to  sensorial  functions,  espe- 
cially to  vision,  and  though  science  is  not  yet  definitely 
settled  concerning  the  subject,  it  is  Ferrier  to  whom  the 
honor  belongs  of  having  sought  these  sensorial  regions 
and  having  to  a  certain  degree  determined  them. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  123 

Vision. — From  excitation  of  the  gyrus  angularis  {pli 
courbe)  in  monkeys,  Ferrier  has  reported  movements  in  the 
eyes  and  head  and  contraction  of  the  pupils.  To  ascertain 
if  reflex  action  was  involved,  Ferrier  abraded  the  gyrus. 
Now  destruction  of  the  gyrus  angularis  on  one  or  both 
sides  did  not  effect  motor  paralysis,  but  it  produced  blind- 
ness of  the  eye  opposite  to  the  side  of  the  lesion.  If  the 
other  gyrus  remains  intact,  supplementation  ensues,  and 
after  a  time  a  restoration  of  vision  to  both  eyes  is  possible. 
On  the  contrary,  if  both  gyri  be  removed,  the  blindness  is 
complete  and  permanent.1 

The  modification  which  this  operation  effects  upon  vision 
it  is  not  easy  to  state;  in  reading  the  details  of  Ferrier's 
experiments,  however,  one  is  convinced  that  destruction  of 
the  gyrus  angularis  produces,  if  not  absolute  loss,  at  least 
a  considerable  disturbance  of  vision. 

From  his  experiments  Ferrier  concludes  that  when  elec- 
tric excitation  of  the  gyrus  angularis  provokes  movements 
of  the  eyes  it  is  the  result  of  a  reflex  action  ;  the  visual 
centres  being  intimately  united  with  the  motor-centres  of 
the  eyes  and  pupils.  As  he  expresses  it,  somewhat  hypo- 
thetically,  excitation  of  the  gyrus  provokes  subjective  vis- 
ual sensations  which  cause  reflex  movements  in  the  eyes. 

Can  Ferrier's  opinion,  localizing  visual  sensations  in  the 
gyrus  angularis,  be  accepted  ?  It  seems  difficult,  and  I 
find,  even  in  the  experiments  themselves  of  that  eminent 
observer,  the  proof  that  such  localization  is  not  at  all 
possible. 

He  observes  that  destruction  of  the  occipital  lobes,  or 
the  posterior  extremities  of  the  hemispheres,  disturbs 
vision  :  he  thinks  this  effect  due  to  the  consecutive  inflam- 
mation having  seriously  affected  the  gyrus  angularis,  but 
perhaps  he  has  given  that  complication  undue  importance. 
The  fact  that  monkeys  or  dogs  can  be  entirely  deprived  of 
the  posterior  part  of  the  encephalon  without  suffering  vis- 

1  Ferrier,  lo~.  cit.,  p.  261  et  suiv. 


124  CEREBRAL   CONVOLUTIONS. 

ual  disturbance  does  not  prove  that  those  regions  have  no 
influence  upon  vision,  provided  supplementation  is  possi- 
ble, and  this  fact,  whatever  difficulties  may  attend  its  in- 
terpretation, is  beyond  doubt. 


Fig.  19. — Monkey's  brain  (after  Ferrier). 
(The  shadings  indicate  locality  of  lesions  which  produce  blindness.) 

In  fact,  the  occipital  lobes  do  have  an  evident  influence 
upon  vision,  as  Vulpian's  experiments  at  the  School  of 
Medicine  positively  demonstrated. 

I  will  also  cite  the  experiments  of  Munck,1  who  removed 
the  occipital  lobes  from  dogs  and  who  says  that  after  re- 
moving the  superior  part  of  the  lobes  there  resulted  psy- 
chical blindness  {Seelenblindheit)  and  from  removal  of  the 
inferior  parts  a  psychical  deafness  (Seelentaubheif). 

I  admit  that  the  psychology  of  Munck,  though  ingenious, 
seems  to  me  rather  subtle,  and  that  the  theory  of  com- 
memorative images  does  not  seem  firmly  established. 
Munck  supposes  that  the  removal  of  certain  portions  of 
the  dog's  occipital  cortex  destroys  the  memory  of  visual 
impressions,  though  in  some  cases  certain  commemorative 
images  remain  in  the  midst  of  the  loss  of  all  others.  "  With 
one,  it  was  the  image  of  a  bucket  from  wJiicJi  it  xvas  accustomed 

1  Zur  Physiologie  der  Grosshirnrinde,  Berl.  Klin.  Woch.,  No.  35,  1877,  p 
505.  This  short  notice  is  translated  almost  textually  in  the  Revue  des  soc. 
méd.,  1878,  t.  xi.,  p.  33. 


FUNCTIONS   OF   THE    CONVOLUTIONS.  1 25 

to  drink  ;  with  another  the  gesture  which  asked  the  dog  to  give 
the  paw"  Aside  from  these  puerilities,  however,  Munck 
has  stated  an  interesting  fact,  that  animals  blinded  by  oc- 
cipital lesion  would  recover  sight  and  learn  again  to  see. 
Also,  if  one  eye  were  removed  from  a  new-born  dog,  the 
occipital  visual  region  of  the  brain  upon  the  opposite  side 
seemed,  after  a  few  months,  to  be  atrophied. 

Concerning  the  visual  functions  of  the  hemispheres  in 
animals  unprovided  with  convolutions,  we  have  the  cele- 
brated experiments  of  Flourens.  These  experiments  inter- 
est us  to  a  certain  point  ;  for  the  cortex  cerebri  in  the 
higher  animals,  with  convolutions,  ought  to  have  analo- 
gous functions  with  the  cortex  cerebri  of  lower  vertebrata, 
which  have  no  convolutions. 

"  A  chicken,  deprived  of  lobes"  says  Flourens,  "  has  really  lost 
sight,  hearing,  etc.  Nevertheless,  none  of  the  senses,  or  rather 
none  of  the  organs  of  sense,  have  been  directly  injured  :  the  eye 
is  perfectly  clear,  the  iris  mobile.  Touch,  hearing,  taste,  all  the 
organs  of  sense  are  untouched,  but  the  perceptions  are  lost  ;  the 
perceptions,  therefore,  do  not  reside  in  the  organs."  1 

This  psychological  physiology  seems  to  me  preferable  to 
Munck's. 

MacKendrick  has  also  studied  the  effects  of  removing 
posterior  and  anterior  parts  of  the  cortex  in  the  pigeon. 
Ablation  of  the  anterior  part  did  not  injure  vision,  but  abla- 
tion of  the  posterior  part  caused  blindness.2 

To  sum  up,  it  may  be  considered  that  visual  impressions 
pass  through  the  posterior  occipital  and  penetrate  regions 
(probably  the  gyrus  angularis)  of  the  cortex  cerebri  ;  but, 
however  probable  it  may  be,  it  is  not  proven  that  con- 
scious visual  perception  is  localized  at  these  points. 

Hearing. — Ferrier  has  endeavored  also  to  ascertain  the 
location  of  auditive  sensation. 

He  employed  two  methods,  electrization  and  abrasion. 


1  Flourens,  Syst.  nerveux,  2d  Edit  ,  p.  91. 
2 Cited  by  Ftrrier,  loc.  cit.,  p.  273. 


1 26  CEREBRAL   CONVOLUTIONS. 

Electrization  of  the  first  temporal  convolution  in  monkeys 
is  followed,  Ferrier  says,  by  different  results,  namely,  the 
opposite  ear  lowers  or  rises  suddenly,  the  eyes  open  widely, 
the  pupils  dilate,  the  eyes  and  head  turn  to  the  opposite 
direction. 

Comparing  these  phenomena  to  those  observed  when  the 
animal  is  surprised  by  a  harsh  noise,  Ferrier  found  them 
to  be  identical,  and  concluded  that  they  arose  from  the  same 
cause,  that  is,  subjective  auditive  sensation,  this  being  pro- 
duced in  one  case  by  excitation  of  the  organs  of  hearing, 
in  the  other  by  excitation  of  the  sensorial  centre. 

The  movements  would  be  due  to  excitation  of  the  motor- 
centres  of  the  ear,  which  excitation,  pursuing  a  very  com- 
plex course  in  the  gray  cortex,  then  passing  by  way  of  the 
cortical  motor-zone,  the  corpora  striata,  the  bulb,  etc., 
would  finally  reach  the  muscles.  Thus  the  movements  of 
the  ear  would  have  reflex  origin. 

Abrasion  of  the  first  temporal  convolution  seemed  to 
render  the  animal  deaf.  The  experiment  is  a  difficult  one, 
for  great  attention  is  requisite  to  recognize  deafness  in  ani- 
mals. Still,  Ferrier  regards  his  experiments  as  decisive. 
"  Auditive  reactions,"  lie  says,  "  from  electric  excitations,  and  the 
absence  of  sucJi  reactions  from  customary  forms  of  auditive  ex- 
citations when  the  first  temporal  convolutions  are  destroyed,  is 
equivalent  to  a  positive  demonstration  of  the  localisation  of  the 
auditive  centre  in  that  region.'" 

Munck  also  locates  auditive  sensation  in  the  temporal 
lobes.  After  the  destruction  of  only  one  of  these  lobes  he 
has  seen  a  gradual  return  of  the  auditive  perceptions. 
Here  then,  as  in  vision,  the  opposite  hemisphere  supple- 
ments. 

Touch. — Localizing  the  sense  of  touch  is  attended  with 
more  difficulties  than  surround  the  other  senses,  not  only 
because  of  the  uncertainty  of  knowing  whether  the  animal 
feels  or  not,  but  also  for  reason  that  the  analysis  of  tactile 
sensation  is  not  yet  sufficiently  complete,  and  it  is  almost 


FUNCTIONS   OF   THE   CONVOLUTIONS.  \2J 

impossible  to  distinguish  tactile  insensibility  from  reflex  and 
from  sensibility  of  pain. 

According-  to  Ferrier,  the  location  of  touch  is  in  the  gyrus 
hippocampi.  The  experiment  upon  which  he  bases  this 
localization  seems  to  me  far  from  conclusive,  and  I  will  not 
here  recite  it.  It  seems  to  me  that  in  the  monkey  upon 
which  he  operated  there  was  a  certain  degree  of  anaesthesia 
of  the  opposite  side,  that  which  belongs,  as  we  have  just 
seen,  to  lesions  of  the  subjacent  white  substance. 

Odor  and  Taste. — Ferrier's  experiments  seem  to  show 
that  the  olfactive  sensations  converge  in  a  definite  region 
of  the  cortex  cerebri,  that  is,  in  the  cornu  Ammonis. 
Moreover,  that  localization  is  in  accord  with  comparative 
anatomy  which  shows  the  connection  between  the  subicu- 
lum  of  the  cornu  Ammonis  and  the  olfactive  lobes. 

By  exciting  the  cornu  Ammonis  in  monkeys,  Ferrier 
produced  movements  in  the  nose  on  the  opposite  side, 
which  might  be  the  indication  of  subjective  olfactive  sen- 
sation. 

With  monkeys  where  the  cornu  Ammonis  was  removed, 
the  most  disagreeable  objects  gave  no  offence  to  either 
taste  or  smell.  On  closing  the  opposite  side  of  the  nose, 
it  could  be  seen  that  the  animal  no  longer  had  any  olfac- 
tive sensation. 

Broca,  by  comparative  anatomy,  reached  the  same  con- 
clusion.1 Unfortunately  1  cannot  enter  into  the  details 
given  by  that  eminent  master,  nor  show  how  close  the 
connection  is  between  the  gyrus  fornicatus,  the  olfactive 
lobe,  and  the  gyrus  hippocampi. 

Hunger  and  Thirst. — We  have  seen  that  according  to 
various  authors  (Hitzig,  Schiff,  etc.),  muscular  sensibility 
was  deranged  when  the  motor  regions  of  the  cortex  cere- 
bri were  injured.  This  localization  is  so  much  the  more 
doubtful  as  it  is  not  yet  certain  that  muscular  sensibility 
exists. 


1  Anat.  comp.  des  circonvolutions  cérébrales,  Revue  d'anthropol.,  1878,  p. 385. 


128  CEREBRAL   CONVOLUTIONS. 

As  for  the  other  sensations,  called  general,  they  have  to 
the  present  been  so  little  studied,  on  accountof  the  extreme 
difficulty  of  physiological  analysis,  that  their  localization 
would  seem  a  premature  attempt.  I  will,  therefore,  con- 
tent myself  with  saying  that  Ferrier  has  localized  hunger 
in  the  occipital  lobes,  sexual  appetite  and  thirst  in  the  re- 
gion of  the  hippocampus.  But  all  this  is  too  hypothetical 
to  detain  us. 

Sensibility  to  Pain. — The  experiments  which  we  have 
before  recounted,  serve  in  a  certain  degree  to  make  known 
to  us  the  localization  of  pain. 

We  have  seen,  in  fact,  that  excitation  of  the  cortex  cere- 
bri in  the  regions  called  motor,  produced,  in  animals  not 
under  anaesthesia,  reactions  indicative  of  a  painful  percep- 
tion, whilst  excitation  of  other  regions  did  not. 

We  have  also  seen  that  upon  removing  the  gray  cortex 
and  exciting  the  white  fasciculi  beneath,  the  same  pheno- 
mena ensue,  and  indications  also  of  a  perception  of  pain. 

The  conclusion  to  be  drawn  from  these  two  orders  of 
facts  undoubtedly  is,  that  pain  does  not  reside  in  the  cells 
of  the  peripheric  gray  cortex,  but  that  in  all  probability  it 
is  located  in  the  ganglionic  axis  of  the  nerve-centres  (cor- 
pora opto-striata,  peduncles,  and  protuberance). 

It  should  be  observed  that  other  experiments  led  Longet 
and  Vulpian  to  consider  the  pons  Varolii  as  the  seat  of  pain 
and  the  scnsorium  commune. 

In  reality  pain  does  not  exist  unless  it  is  perceptible, 
conscious,  and  the  seat  of  pain  is  probably  the  seat  of  con- 
sciousness (sensorium  conscium). 

Pathology,  which  has  taught  so  much  concerning  motor 
functions,  has  not  furnished  us  yet  with  a  satisfactory  solu- 
tion respecting  the  sensory  functions  of  the  convolutions. 
In  other  words,  one  cannot  produce  a  chapter  of  cortical 
anaesthesias  to  place  by  the  side  of  the  existing  chapter  of 
cortical  paralyses. 

Still,  clinical  experience  and  pathological  anatomy  are 
able  to  indicate  cases  of  hemianaesthesia  from    cerebral 


FUNCTIONS   OF   THE   CONVOLUTIONS.  1 29 

lesions.  These  are  the  cases  which,  joined  to  the  experi- 
mental knowledge  that  we  have  briefly  outlined,  may  be 
sufficient  to  establish — of  course,  with  such  reserve  as  the 
obscurity  and  difficulty  of  the  subject  imposes — the  part 
taken  by  the  convolutions  in  general,  or  special  sensations. 

L.  Tiirk,  and  above  all  Charcot  and  his  pupils,  have 
fully  demonstrated  the  fact  that  hemianaesthesia  always 
follows  a  lesion  of  the  posterior  part  of  the  internal  cap- 
sule, that  is,  the  band  of  white  substance  which  separates 
the  optic  thalamus  from  the  lenticular  ganglion  of  the  cor- 
pus striatum.1 

Hemianesthesia  results  from  a  lesion  of  the  internal 
capsule  ;  consequently  the  sensorial  fasciculi  conducting 
impressions  from  the  periphery  to  the  sensor  him  commune 
go  by  way  of  the  internal  capsule. 

If  the  sensorium  commune  be  located  in  the  cortical  layer 
of  the  brain,  the  phenomena  observed  can  be  very  well 
explained  by  a  simple  interruption  of  conduction.  But  if 
the  sensorium  be  located  in  the  protuberance,  it  must  be 
admitted  that  the  sensorial  fibres  going  to  the  occipital 
lobes  are  reflected,  and  return  by  the  same  way  in  the 
protuberance.  It  cannot  be  admitted  that  in  man  the  re- 
turn is  made  by  way  of  the  motor-zone,  for  the  reason  that 
lesions  of  the  middle  and  anterior  parts  of  the  diverging 
fibres  affect  neither  vision,  hearing,  nor  sensibility.  Per- 
haps, also,  it  might  be  thought  that  the  sensorium  commune 
does  not  exist,  and  that  if  the  general  sensibility  resides  in 
the  cerebral  ganglionic  centres,  visual  sensation  resides  in 
the  occipital  lobes.  Again,  it  might  be  supposed  that  in 
the  dog's  brain,  which  is  so  different  from  that  of  man's, 
the  course  of  sensorial  impressions  is  not  the  same. 

It  will  be  understood  why  I  do  not  dwell  upon  these 
hypotheses  any  more  than  I  did  upon  the  interesting  phe- 
nomena of  sensorial  hemianesthesia. 

'Charcot  :  Leçons  sur  les  localisations,  1876,  p.  80  et  suiv.  American  éd., 
p.  63  et  suiv. 


130  CEREBRAL   CONVOLUTIONS. 


Sec.  3.  INTELLECTUAL  FUNCTIONS  OF  THE 
CONVOLUTIONS. 

I  do  not  believe  that  at  the  present  time  this  question 
can  be  properly  treated.  Its  solution  is  probably  reserved 
for  the  age  to  come,  which,  joining  the  present  researches 
to  its  own,  may  be  able  to  establish  psycho-physiological 
laws  upon  a  firm  basis. 

Still,  by  availing  ourselves  of  the  gifts  of  embryology, 
comparative  anatomy,  pathology,  and  experimental  physio- 
logy, we  may,  to  a  certain  point,  establish  a  relation  be- 
tween intellectual  phenomena  and  the  convolutions. 

Comparative  anatomy  shows  us  that,  with  mammifera, 
intellectual  activity  is  in  proportion  to  the  development' of 
their  convolutions. 

Thus,  man  has  very  numerous  and  rich  convolutions. 

After  him,  and  at  a  very  great  distance,  come  first  the 
anthropoids,  then  other  monkeys  ;  then  the  elephant,1  then 
the  whale,  then  carnivora. 

Rodents,  whose  intelligence  is  very  mediocre,  have  no 
convolutions  ;  they  are  scarcely  indicated. 

Dareste  supposed  that  convolutions  existed  only  with 
animals  of  large  size  ; 2  this  is  but  partly  true.  The  castor, 
for  example,  has  no  convolutions,  whereas  the  striped 
monkey  has  many  ;  but  what  a  difference,  too,  between 
the  intelligence  of  one  and  the  instinct  of  the  other! 

Thus,  from  their  connection,  we  may  suppose  that  in- 
telligence is  a  function  of  the  convolutions.  It  should  be 
added,  that  from  the  rodent  to  man,  not  only  the  convo- 
lutions augment  in  number  and  extent,  but  also  the  brain 
augments  in  weight.  If  the  proportion  between  the  weight 
of  the  brain  and  that  of  the  body  be  noted,  it  will  be  seen 

1  See  piate  of  Leuret.  a  Ann.  de  se.  nat.,  1865,  t.  iii.,  p.  65. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  131 

that  in  man  the  body  weighs  45  or  47  times  more  than  the 
brain  ;  with  the  horse  it  is  400  times  greater,  with  the  ele- 
phant 500,  the  ox  800  (Leuret). 

Study  of  the  convolutions,  according  to  age  and  race, 
leads  to  analogous  conclusions.  The  weight  of  the  brain 
and  the  richness  of  the  convolutions  increase  with  intelli- 
gence. 

Concerning  the  weight  of  the  brain,  here  are  some  figures 
by  Davis:1 

21   English, 1425  gr. 

25  Chinese, 1,357     " 

5   Esquimaux,  ....  1,396     " 

9  Negroes,  .....      1,322     " 

17  Australians,  .         .         .         .         1,197     " 

Very  accordant  results  have  been  observed  by  other 
authors,  and  it  may  be  regarded  as  certain  that,  in  the  white 
race,  the  weight  of  the  brain,  either  absolute  or  relatively 
to  the  body,  is  greater  than  in  other  races. 

There  is  also  a  difference  in  the  forms  of  the  convolu- 
tions. 

For  comparable  elements,  it  will  be  necessary  to  take 
the  convolutions  of  anthropoids,  inferior  human  races,  foe- 
tuses, idiots,  and  superior  races. 

In  monkeys,  even  of  the  highest  order,  the  gorilla  for 
example,  the  convolutions  are  very  undeveloped  as  com- 
pared with  man's.2  Still,  the  two  brains  are  constructed 
absolutely  upon  the  same  model,  and  of  all  animals  the 
anthropoids  have  the  best  developed  convolutions. 

The  same  may  be  said  respecting  the  brain  of  the  Char- 
mas, which  is  nearly  simian.  By  the  following  cut, 
borrowed  from  Leuret,  it  can  be  seen  how  simple  and 
elementary    the     convolutions    of    the    parieto-temporal 

1  Cited  by  Pozzi,  Revue  critique  sur  le  poids  du  cerveau  ;  Revue  d'anthro- 
pol.,  1878,  p.  277.  I  refer  to  that  article  for  bibliographie  and  other  details 
into  which  I  cannot  enter. 

-  See  pi.  ii.,  fig.  2  in  Broca's  mémoire:  Sur  le  Cerveau  du  Gorille.  Revue 
d'anthrop.,  1 37S,  p.  1. 


13: 


CEREBRAL   CONVOLUTIONS. 


regions  are,  especially  at  the  point  where  the  parallel 
fissure  becomes  buried  in  the  parietal  lobe.  The  temporal 
convolution  which  ascends,  to  form  the  convolution  of 
the  gyrus  angularis,  is  extremely  simple,  without  annec- 
tant  or  transition  gyri,  and  if  the  brain  be  compared  with 
that  of  a  European,  the  difference  between  the  simplicity 
of  the  one  and  the  complexity  of  the  other  will  be 
striking.1 


Fig.  20. — Brain  ot  die  adult  Charmas  (after  Leuret). 

It  should  be  observed  though,  that  in  some  Europeans, 
feeble  in  intelligence  or  imbecile,  and  in  some  criminals, 
there  is  the  same  exterior  formation,  the  same  simplicity 
of  convolutions.  In  the  accompanying  figure  (fig.  21)  of 
the  brain  of  Fieschi,  also  borrowed  from  Leuret,  can  be 
seen  the  extreme  simplicity  of  the  temporal  lobe. 

The  sulci  which  separate  the  three  temporal  convolu- 
tions'are  straight,  parallel,  without  flexures  ;  to  a  certain 
degree  it  is  of  the  simian  type. 

To  these  may  be  compared  Pozzi's  excellent  illustration 
of  the  brain  of  the  imbecile,  Marie  Martel.2     The  poste- 

1  For  example,  see  fig.  440.    Traité  d'anat.     Sappey,  p.  63. 

2  Art.  Convois,  du  Diet.  Ency.,  figs.  6,  7,  and  S,  pp.  352,  354,  and  355. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  1 33 

rior  parietal  and  temporal  convolutions  are  extremely 
simple.  It  may  be  seen  also  that  the  frontal  convolutions 
are  straight,  simple,  and  narrow,  and  the  paucity  of  folds 
is  general,  equally  marked  in  all  the  lobes  and  all  the  con- 
volutions. 

It  is  interesting  to  compare  with  these  primitive  brains 
the  brains  of  the  fœtus  or  of  new-born  infants,  in  whom  no 
intelligence  yet  exists.  In  these,  the  secondary  convolutions 
are  not  developed.  It  is  only  at  about  the  age  of  puberty 
that  the  organ  is  entirely  developed  and  its  functions  estab- 
lished.1 


Fig.  21. —  The  brain  of  Fieschi  (Leuret). 

If  we  add  to  this  the  astonishing  resemblance  which 
some  microcephalic  brains  bear  to  the  brains  of  monkeys,2 
it  may  perhaps  be  concluded  that  intelligence  and  richness 


1  See  fig.  21  of  Ecker,  in  art.  of  Pozzi,  loc.  cit.,  p.  384. — Also  Luys,  Bull, 
de  la  Soc.  de  Biol.,  1876,  p.  230,  Cerveau  d'une  imbecile  :  Lebon,  Comptes 
rendus  de  l'Acad.  des  Sciences,  1S78,  8  juillet. 

2  See  pi.  xxiv.,  Leuret,  Atlas,  p.  36,  figs.  4,  5,  and  6. 

10 


134  CEREBRAL   CONVOLUTIONS. 

of  convolutions,  more  particularly  it  may  be  of  the  poste- 
rior parietal  and  occipital,  maintain  a  close  relationship. 
It  is  possible  also  that  the  frontal  convolutions  are  more 
developed  in  proportion  to  the  degree  of  intelligence.  It 
seems,  indeed,  that  intellectual  labor  appears  to  increase 
the  volume  of  the  frontal  lobes.1 

An  attempt  has  been  made  to  establish  a  difference  be- 
tween human  races  based  upon  developed  foreheads  as 
representing  intelligence  and  developed  occiput  as  a  mark 
of  inferiority,  but  the  distinction  is  not  established,  as  the 
development  of  the  occipital  regions  which  encroach  upon 
and  cover  the  cerebellum  is  one  of  the  features  which 
most  distinguishes  the  human  brain. 

As  Broca  said,  symmetry  of  the  convolutions  seems  to 
indicate  an  inferiority.2  The  human  brain  is  much  more 
asymmetrical  than  that  of  the  monkey  or  of  animals.  In 
idiots,  microcéphales,  etc.,  the  hemipheres  often  are  sym- 
metrical. At  the  same  time,  the  brains  of  idiots  often  are 
very  asymmetrical. 

As  a  rule,  the  female  brain  is  less  rich  in  convolutions 
than  the  male,  and  its  weight,  as  compared  to  the  weight 
of  the  body,  is  also  less:  here,  too,  intelligence  and  the 
greater  or  less  development  of  the  convolutions  are  in 
unison. 

In  short,  the  brains  of  those  feeble  in  intellect  and  infe- 
rior in  type  have  less  weight  and  greater  poverty  of 
convolutions.  It  is  the  reverse  in  brains  of  those  highly 
intelligent.  Cuvier's  brain  weighed  1,829  grammes  ;  those 
of  Cromwell  and  Byron  weighed  still  more,  if  figures  not 
very  well  authenticated  can  be  accepted.3 

Recent  autopsies,  the  only  ones  possessing  any  value,  as 
it  is  only  since  Leuret  and  Gratiolet  that  the  morphology 

1  Lacassagne  et  Cliquet,  De  l'influence  du  travail  intellectuel  sur  le  volume 
et  la  forme  de  la  tête. — Bull,  de  la  soc.  de  méd.,  pub.  1878,  p.  398. 

2  Bull,  de  la  Soc.  d'anthrop.,  1866,  p.  393. 

3  See  Wagner,  Recherches  sur  les  fonctions  du  cerveau,  Journ.  de  la  physiol., 
iv.,  p.  554- 


FUNCTIONS   OF  THE   CONVOLUTIONS.  135 

of  the  convolutions  has  been  known,  leave  us  almost  com- 
pletely in  default,  and  the  question  may  be  considered  as 
still  under  consideration.1 

It  is  possible  that  the  relation  between  intelligence  and 
the  measure  of  convolutions  and  weight  of  brain  would 
not  present  the  seeming  irregularities  observed,  if  the  con- 
volutions of  the  brain  could  be  unfolded,  as  Gall  proposed. 
I  am  not  sure  whether  that  unfolding  could  be  effected 
even  to  an  approximative  degree  ;  but  that  would  be  an 
important  element  of  knowledge,  in  order  to  judge  of  the 
quantitative  value  of  the  gray  substance  of  the  brain. 

Again,  perhaps  it  is  not  only  the  quantity,  but  also  the 
quality  (?)  of  the  gray  substance  which  plays  an  important 
part. 

Let  us  see  now  whether  experimental  physiology  and 
pathological  anatomy  will  furnish  more  positive  ideas  re- 
specting the  intellectual  functions  of  the  convolutions  than 
comparative  anatomy  does. 

Experimental  physiology  reveals  little  ;  the  most  precise 
knowledge  thus  far  from  this  source  is  derived  from  the 
admirable  experiments  of  Flourens.  When  the  cerebral 
lobes  are  entirely  removed  from  birds  or  reptiles,  vision, 
hearing,  and  intelligence  are  abolished.  They  no  longer 
possess  volition  ;  their  movements  are  reflex  and  involun- 
tary ;  and  although  they  are  appropriate  to  the  result,  still 

1  "  The  weight  of  Sir  Jas.  Simpson's  brain  (1870),  including  the  cerebellum, 
was  1,530  grammes.  The  convolutions  were  remarkably  numerous,  besides 
which,  they  were  bent  and  interlaced  as  though  the  skull  afforded  insufficient 
room.  The  island  of  Reil-was  astonishingly  developed."  Revue  d'Anthrop., 
1872,  p.  124.  Dante's  skull  was  remarkable  for  the  enormous  size  of  the 
frontal  lobes  (Broca,  Bull,  de  la  Soc.  d'anthrop.,  1866,  p.  206). — Gratiolet  also 
mentions  the  marvellous  form  of  Descartes'  head  (ibid.,  1861,  p.  71). — For 
descriptions  of  brains  of  idiots  or  imbeciles,  I  will  specially  refer  to  the  Journal 
of  Mental  Sciences  and  to  the  West  Riding  Lunatic  Asylum  Reports. — Luys 
has  called  attention  to  a  supplementary  convolution,  which,  lying  parallel  to 
the  post-Rolandic,  joins  the  temporal  to  the  superior  parietal  lobe  ;  but  it  is 
not  certain  that  the  existence  of  that  convolution  coincides  with  greater  intel- 
lectual activity.  Bull,  de  la  Soc.  de  Biol.,  1876,  p.  222. — See  also  Vulpian's 
lessons  upon  the  Physiologie  du  système  nerveux,  p.  68S. 


I36  CEREBRAL   CONVOLUTIONS. 

they  in  reality  are  entirely  regulated  by  the  intensity  and 
nature  of  the  excitation. 

A  great  number  of  all  kinds  of  experiments  have  been 
made  upon  the  convolutions  of  mammifera,  but  the  con- 
clusions are  still  uncertain  and  obscure. 

The  Rolandic  zone  can  be  destroyed  without  altering 
the  intelligence  ;  also,  a  considerable  portion  of  the  fron- 
tal, or  even  the  occipital  lobes,  can  be  removed  without 
an  apparent  alteration  of  the  intellectual  functions  ;  but  a 
decision  is  so  difficult,  and  the  interpretation  so  debatable, 
that  as  yet  there  is  nothing  established  in  this  mysterious 
question.  It  is  possible,  however,  that  the  blindness  and 
deafness,  caused  by  destruction  of  the  occipital  lobes,  and 
perhaps,  also,  the  ruining  of  other  ill-comprehended  func- 
tions, may  throw  the  animal  into  a  state  of  stupor  nearly 
equivalent  to  the  loss  of  intelligence. 

If  all  the  considerations  hitherto  presented  in  this  work 
be  taken  into  account,  we  will  be  forced  to  recognize  that 
animal  physiology  is  incapable  of  resolving  the  question  ; 
for  concerning  intellectual  faculties,  no  comparison  what- 
ever can  be  instituted  between  man  and  animal. 

To  elucidate  the  two  following  problems,  then,  pathol- 
ogy should  be  interrogated  : 

1  st.  Is  intelligence  located  in  the  convolutions? 

2d.  In  what  convolutions  are  the  various  intellectual 
faculties  located  ? 

For  man,  life  without  the  brain  is  impossible,  though 
there  are  numerous  cases  of  the  destruction  of  one  lobe 
(frontal,  occipital,  or  parietal),  or  of  two  corresponding 
lobes  (the  two  frontal  for  example),  without  destruction 
of  intelligence.1  It  may  be  said  that  instances  are  not  in- 
frequent where  the  frontal  lobes  have  been  traversed  by  a 
ball,  and  yet  the  intelligence  retained,  or  rather,  nearly  so. 

Experiments  upon  animals  give  the  same  results,  and  the 


1  Among  other  cases,  one  cited  by  Vulpian,  loc.  cit.,  p.  70.     See  also  Mire, 
Rec.  de  méd.  militaire,  juin,  1871. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  1 37 

following  proposition  may  be  deduced  ;  one  that  thus  far 
has  not  been  invalidated. 

There  is  no  region  upon  the  surface  of  the  convolutions 
especially  assigned  to  intellection. 

Still,  there  is  evidently  one  localization  of  intellection  : 
aphasia  has  served  to  localize  the  function  language,  and 
perhaps  that  will  make  possible  an  explanation  of  the  na- 
ture of  intelligence. 

Intelligence  seems  to  be  the  union  of  various  faculties, 
and  language  is  one  of  those  faculties.  Thus  the  intelli- 
gence of  an  aphasiac  is  impaired  in  one  of  its  constituent 
elements,  and  there  is  an  intellectual  diminution.  A  man 
with  his  mouth  closed  might  have  all  his  memory,  judg_ 
ment,  and  imagination.  That  man  would  not  be  an  apha- 
siac ;  on  the  other  hand,  observation  shows  that  there  does 
not  exist  an  aphasiac  with  full  memory,  judgment,  and 
imagination.  Perhaps  there  may  be  other  faculties  local- 
ized, like  language,  in  a  convolution.  But  what  are  the 
faculties  which,  gathered  into  a  fasciculus,  constitute 
human  intelligence  ?  Can  we  hope  to  find  another  lacultv 
so  well  defined  psychologically  as  is  that  of  language  ? 

We  will  enter  no  further  upon  this  subject  which  is  too 
metaphysical  and  too  open  to  debate  ;  we  will  only  add  a 
few  words  respecting  general  paralysis  of  the  insane. 

Since  Calmeil  and  Parchappe,  it  is  known  that  the  ana- 
tomical lesion  in  this  affection  is  an  alteration  in  the  gray 
cortical  substance,  according  to  modern  authors,  in  the 
deep  '  layer  of  it. 

Would  that  region  be  really  the  seat  of  intelligence  ?  It 
is  very  hypothetical.  All  that  can  be  said  is,  that  very 
probably  the  gray  cortex  of  the  brain  is  the  organ  of  the 
intellectual  functions. 

With  general  paralytics  of  long  standing,  having  arrived 
at  the  last  degree  of  dementia,  and  in  senile  dementia,  the 
gray  substance  is  found  to  be  atrophied,  invaded  by  con- 
junctive tissue,  having  in  fact  almost  disappeared. 

1  Meschécie,  Allg.  Zeitsch.  fiir  Psychiatrie,  1873. 


138  CEREBRAL   CONVOLUTIONS. 

It  is  probable  that  accesses  of  delirium  in  general  par- 
alytics coincide  with  extensions  of  congestion.  It  is  known 
to  the  medical  attendants  of  the  insane  that  the  delirium 
of  congestion  is  an  exalted  kind  '  {ambitieux). 

There  is  a  manifest  relation  between  the  quantity  of 
blood  which  circulates  in  the  superficial  layers  of  the  brain 
and  the  conception  of  certain  delirious  ideas.2 

Again  it  is  known  that  alterations  of  the  intelligence 
from  poisons,  that  is  to  say,  functional  disturbance  in  the 
gray  cortical  substance,  first  affect  the  voluntary  conscious 
faculties,  and  afterwards  the  involuntary,  unconscious  ones. 
It  is  not  amiss  to  recall  the  fact  that  the  same  substances 
which  abolish  reflex  action  (chloroform,  morphine,  alcohol, 
etc.),  are  also  the  substances  which  abolish  intelligence. 
Poisons  to  the  gray  substances  of  the  spine  (poisons  of  the 
reflexes)  are  also  poisons  of  the  gray  cortical  substance 
(poisons  of  intelligence).  The  fact  that  a  few  drops  of 
alcohol  introduced  into  the  circulation  produce  furious 
delirium  explains  the  reason  why,  in  many  cases  of  short- 
standing  insanity,  no  cerebral  lesion  can  be  discovered, 
either  by  the  naked  eye  or  with  the  microscope  ;  it  is 
from  the  reason  that,  besides  an  alteration  of  form,  there  is 
probably  also  a  dynamic,  functional  alteration  which  is 
beyond  our  present  means  of  detection. 

If  in  a  few  lines  we  would  now  embrace  a  conclusion  of 
this  work,  too  hasty  to  escape  imperfection  :  we  would  say 
that  the  brain  is  not  a  simple  organ,  and  that  it  would  be  a 
false  path  to  seek  therein  a  general  focus  uniting  all  im- 
pulses, impressions,  and  volitions. 

The  inferior  vertebrata  are  very  simple  beings  ;  their 
movements  are  nearly  automatic  and  seem  to  be  reflexes 


1  Perhaps  there  should  be  some  reserve  respecting  the  congestion  of  paraly- 
tics.    See  Charcot,  Leç.  sur  les  maladies  du  système  nerveux,  t.  i.,  p.  251. 

2  Moreau  has  often  told  me  of  a  cobbler,  a  general  paralytic,  who,  during  con- 
gestion, believed  himself  the  pope.  Bleeding  calmed  the  congestion  and  stop- 
ped the  delirium,  but  whenever  the  flow  of  blood  was  stopped,  by  placing  the 
fingers  over  the  opening,  he  again  became  pope. 


FUNCTIONS   OF   THE   CONVOLUTIONS.  1 39 

of  the  least  possible^  complication.  But  as  one  ascends 
the  scale,  a  perfecting  apparatus  becomes  added  to  that 
primitive,  almost  embryonic  system.  That  apparatus 
is  the  cerebral  gray  cortex.  The  more  the  psychical,  sen- 
sorial, and  ideo-motor  functions  are  developed,  the  more 
the  apparatus  which  is  destined  to  their  use  also  acquires 
development.  In  the  superior  mammifera  this  layer  of 
nerve-substance  has  to  assume  folds  and  irregular  volu- 
tions in  order  to  find  room  in  the  cranial  cavity.  It  is  in 
this  layer  that  the  intellectual  functions  are  elaborated,  and 
from  thence  also  come  the  psycho-motor  impulsions. 

The  route  taken  by  these  impulsions  is  now  known  ;  it 
is  by  way  of  the  white  fasciculi  neighboring  the  fissure  of 
Rolando. 

Along  with  these  motor  impulsions  there  are  others, 
probably  involuntary  and  unconscious,  located  in  the  gan- 
glionic axis  surrounding  the  central  canal. 

It  can  be  imagined  that  in  the  superior  mammifera,  espe- 
cially in  the  monkey  and  in  man,  there  is  a  kind  of  dual  ex- 
istence ;  the  one  a  simple  reflex  with  which  the  cortical 
apparatus  has  nothing  to  do  ;  the  other  a  complex  reflex, 
intellectual,  in  which  the  sensorial,  conscious  impressions, 
passing  through  the  occipital  layers,  become  elaborated 
by  the  entire  cortex  cerebri  and  then  returned  by  way  of 
the  parietal  white  fasciculi  as  voluntary  motor-excitations. 

But  even  this  is  as  yet  hypothetical  and  long  researches 
are  still  requisite  to  build  up  (or  destroy)  the  theory. 

Everywhere  are  found  so  many  hypotheses  and  so  few 
certainties  that  discouragement  might  well  ensue  upon 
beholding  the  colossal  efforts  of  an  age  of  research  pro- 
ducing results  so  contestable.  But  such  discouragement 
would  be  unjustifiable,  for  each  day  brings  progress,  and 
the  moment  will  come,  perhaps  is  near  at  hand,  when  the 
functions  of  the  convolutions,  that  is  to  say,  intelligence, 
will  be  understood,  as  are  the  functions  of  the  heart,  the 
muscles,  and  the  blood. 


END. 


BIBLIOGRAPHY. 


A  number  of  critical  reviews,  physiological  and  patho- 
logical, have  appeared  upon  the  question  of  localizations, 
and  also  some  interesting  works  not  directly  related  to 
physiology. 

I  subjoin  a  list  of  some  of  the  principal  ones  : 

UODDS.  Localization  of  Functions  of  the  Brain,  being  an  histor- 
ical and  critical  analysis  of  the  question.  Jour,  of  Anat. 
and  Phys.,  t.  xii.,  p.  340. 

RENDU  AND  GOMBAULT.  Des  localisations  cérébrales.  Re- 
vue des  se.  méd.,  t.  vii.,  1876,  pp.  236  and  765. 

LEPINE.  Revue  mens,  de  méd.  et  chir.,  mai,  1877,  p.  381. 

BOURDON.  Recherches  sur  les  centres  moteurs  des  membres. 
Bull,  de  l'Acad.  de  méd.,  23d  Oct.,  1877. 

POZZI.  Des  localisations  cérébrales  et  des  rapports  du  crâne  avec 
le  cerveau  au  point  de  vue  de  la  trépanation  (Arch.  gén.  de 
méd.  Ar.,  1877). 

GLIKY.  Ueber  die  Wege  auf  denen  die  durch  elektrische 
Reizung  der  Grosshirnrinde  erregten  motorischen  Thâtig- 
keiten  durch  das  Gehirn  hindurch  fortgeleitet  werden  (Eck- 
hard's  Beitrâge,  etc.,  t.  vii.,  p.  177.) 

VETTER.  Ein  Ueberblick  ueber  die  neueren  Expérimente  am 
Grosshirn.     Deutsch.  Arch,  fiir  klin.  Med.,  xv.,  p.  350. 

CZARNOWSKI.  Ein  Beitragzur  Lehre  von  den  motorischen  Cen- 
tren  der  Grosshirnrinde.     Diss,  inaug.,  32  p.,  Breslau,  1874. 

ONIMUS.  Des  erreurs  qui  on  pu  être  commises  dans  les  expéri- 
ences physiologiques  per  l'emploi  de  l'électricité  (Gaz.  hebd., 

1877). 

SEGUIN.  A  Contribution  to  the  Study  of  localized  cerebral 
Lesions.  Rep.  from  the  Trans,  of  the  Amer.  Neurol.  Assoc, 
New  York,  1S77. 

BORDIER.  F.evue  critique  des  localisation  cérébrales. — Rev. 
d'anthrop.,  1877,  p.  265. 


142  CEREBRAL   CONVOLUTIONS. 

GRASSET.  Des  localisations  dans  les  maladies  cérébrales,  2d 
Edit.,  Montpellier,  1878  (a  very  good  and  complete  work). 

ATKINS.  Revue  sur  les  localisations.  Dublin  Jour,  of  Med.  Sci- 
ence, July,  1877,  p.  50. 

NEWCOMBLE.  Epileptiform  Seizures  in  general  Paralysis. 
West  Riding  Lun.  Asylum  Reports,  1875. 

A.  FOVILLE,  son.  Des  relations  entre  les  troubles  de  la  motilité 
dans  la  paralysie  générale  et  les  lésions  de  la  couche  corti- 
cale des  convolutions  fronto-parietales.  Ann.  méd.  psychol., 
Dec,  1876,  Jan.,  1877. 

MATHIAS-DUVAL.  Localisations  cérébrales  dans  les  hémi- 
sphères.    Trib.  méd.,  1877,  p.  248. 

BURCKHARDT.  Des  centres  fonctionnels  du  cerveau.  Zeitsch. 
fur  Psych.,  1877. 

FERRIER.  Lectures  on  the  Localization  of  Cerebral  Diseases. 
Brit.  Med.  Jour.,  1878,  Nos.  899,  904,  p.  399,  etc. 

TAMBURINI.  De  l'état  actuel  de  la  physiologie  normale  et 
pathologique  de  l'intelligence.     Lo  Sperimentale,  févr.  1877. 

OBERSTEINER  et  EXNER.  Mesure  de  la  vitesse  de  la  pen- 
sée chez  les  aliénés.     Arch,  fiir  Pathol.  Anat.,  1873-1874. 

BESSER.  Réflexe  der  Neugebornen.  Arch,  fiir  Psychiatrie,  t. 
vii.,  p.  460. 

BALOGH,  HILAREWSKI,  HOLMGREN,  WELIKY.  Being 
various  works  in  Hungarian,  Swedish,  and  Russian,  analyzed 
in  the  Jahresbericht  fur  Anat.  Physiol.,  pp.  35  to  40,  1876. 
Hilarewski  holds  that  the  convolutions  have  no  vaso-motor 
action;  on  the  contrary,  Balogh  considers  that  the  hemi- 
spheres influence  the  cardiac  rhythm.  Lastly,  Weliky  limits 
diffusion  to  three  millimetres. 


POISONS  OF  THE  INTELLIGENCE. 


POISONS  OF  THE  INTELLIGENCE. 


ALCOHOL,    CHLOROFORM,    HASCHISCH,    AND 

COFFEE. 

I. 

M.  Claude  Bernard  defines  a  poison  as  a  substance 
which  cannot  enter  into  the  composition  of  the  blood  nor 
penetrate  into  the  organism  without  causing-  transient  or 
permanent  disorders.  Thus  we  distinguish  a  poison  from 
an  aliment,  since  the  latter  is  an  assimilable  substance  that 
should  form  part  of  the  blood  or  other  tissues,  while  the 
former  should  be  eliminated  and  disappear.  All  medicines 
are  poisons  and  the  converse,  if  we  use  the  word  poison  in 
its  proper  and  scientific  sense.  The  early  experiments 
with  poisons  were  merely  for  the  purpose  of  clearing  up 
medico-legal  problems  ;  now  we  recognize  experimental 
toxicology  as  part  of  the  study  of  therapeutics.  A  great 
advance  was  made  in  the  attempt  to  limit  the  action  of  poi- 
sons to  single  organs  or  tissues,  and  this  progressive  period 
may  be  said  to  date  from  the  brilliant  experiments  of  M. 
Claude  Bernard  upon  the  action  of  curare. 

The  principle  of  life  resides  in  no  particular  organ  or 
tissue,  but  is  disseminated.  A  living  being  is  one  that  is 
composed  of  living'organs  which  candie  separately.  These 
organs  are  composed  of  tissues,  and  these  again  of  cellules, 
and  all  may  disappear  successively  without  the  death  of 
one  being  necessarily  followed  by  that  of  the  others. 

Carbonic  oxide  acts  on  the  red  globules  of  the  blood,  and 
death  from  charcoal-poisoning  is  the  consequence  of  the 
poisoning  of  this  particular  anatomical  element  by  carbonic 
oxide.     Therefore  the  blood  dies  before  the  other  tissues, 


146  POISONS   OF   THE   INTELLIGENCE. 

and  if  these  finally  perish  it  is  because  they  are  deprived 
of  living  blood  which  is  essential  for  their  existence.  The 
same  process  occurs  in  death  from  hemorrhage.  Physio- 
logical analysis  goes  even  farther  than  this,  for  not  only 
are  the  red  globules  acted  upon,  but  a  particular  consti- 
tuent of  the  red  globules,  haemoglobine. 

Unfortunately  the  same  accurate  knowledge  does  not 
extend  to  the  action  of  all  poisons.  We  know  that  the 
blood,  muscles,  spinal  cord,  and  nerves  have  properties 
that  are  perverted  or  destroyed  by  special  poisons,  but  our 
information  rarely  goes  beyond  this  primary  localization. 

By  poisons  of  the  intelligence  we  mean  those  whose  pri- 
mary action  affects  the  processes  of  intellection.  This 
may  not  be  their  exclusive  action,  for  other  organs  and 
functions  may  suffer  afterwards,  but  it  is  the  predominant 
action.  The  intelligence  is  attacked  before  any  other  func- 
tional troubles  appear,  but  these  must  follow,  for  the  cen- 
tral nervous  system  presides  over  muscular  movements 
and  the  functions  of  all  the  organs  and  apparatus  of  the 
body,  while  at  the  same  time  it  is  the  organ  of  intelligence. 
So  chloroform,  which  begins  by  suppressing  the  will,  mem- 
ory and  ideation,  functions  of  the  brain,  ends  by  paralyz- 
ing the  movements  of  the  heart  and  respiration,  functions 
of  the  spinal  cord.     Strychnine  acts  in  a  reverse  way. 

If  we  consider  the  nervous  system  as  having  three  prin- 
cipal functions,  intelligence,  which  depends  upon  the 
cerebrum,  voluntary  movements,  depending  upon  the  spi- 
nal cord,  and  organic  movements  of  the  heart,  digestive 
apparatus  and  glands,  depending  on  the  medulla  oblongata, 
we  shall  find  some  poisons  acting  first  on  one  or  the  other 
of  these  parts  and  upon  the  functions  which  they  control, 
though  finally  upon  all  parts  of  the  nervous  system. 

We  shall  consider  only  those  which  act  upon  the  brain 
and  disturb  the  intellectual  functions.  We  shall  not  seek 
to  determine  how  they  act,  since  this  is  unknown,  but  en- 
deavor to  give  as  clear  an  analysis  of  their  symptoms  as 
possible. 


ALCOHOL,   CHLOROFORM,    HASCHISCH,   AND   COFFEE.     147 


LI. 
ALCOHOL. 

The  chief  characteristic  of  all  poisons  of  the  nervous 
system  is  that  they  excite  before  they  destroy,  and  it  is  the 
pleasure  of  this  sur-excitation  that  is  habitually  sought  by 
drunkards.  The  first  effect  of  alcoholic  intoxication  is  a 
secret  sense  of  satisfaction,  a  most  agreeable  beatitude. 
The  ideas  seem  to  clear  up,  difficulties  vanish,  life  is  rose- 
colored,  and  full  of  contentment  and  happiness.  If  one 
continues  to  drink,  the  intellectual  excitation  augments 
and  shows  itself  in  various  ways.  We  may  sum  up  all 
these  forms  in  one  word  by  calling  it  a  condition  of  hyper- 
ideation. 

In  this  condition  there  is  a  profusion  of  ideas  and  fancies 
of  the  most  varied  and  opposite  character  which  succeed 
one  another  with  great  rapidity.  That  which  distinguishes 
them  is  their  lack  of  moderation.  There  is  no  measure 
for  the  intelligence,  all  is.  out  of  order  and  expansive. 
They  feel  the  moral  forces  increased  tenfold,  they  think 
themselves  capable  of  undertaking  anything  and  accom- 
plishing anything.  Meantime  new  ideas  follow  each  other 
without  cessation  ;  all  are  impracticable,  but  all  amuse  for 
the  moment  until  they  vanish  and  others  appear.  Perhaps 
in  the  number  there  is  something  rational,  but  they  have 
no  time  to  grasp  it.  There  is  a  perpetual  to-and-fro 
motion  of  the  fancy' a  mental  '  will-o'-the-wisp  '  dance,  more 
or  less  seductive,  in  which  they  cannot  find  time  to  make  a 
pause.  In  this  condition  it  is  impossible  for  them  to  keep 
secrets,  they  become  confidential  and  effusive.  This 
tendency  is  manifested  even  in  a  slight  degree  of  intoxica- 
tion, but  in  a  more  advanced  condition  there  is  no  confidence 
that  can  be  kept.  This  hyper-ideation  is  chiefly  an  excess 
of  imagination,  and   there  are  some  authors  who  cannot 


148  POISONS   OF  THE   INTELLIGENCE. 

write  unless  in  this  condition  of  sur-excitation  which  gives 
to  their  works  a  factitious  stamp  of  originality. 

Often  while  intoxicated,  in  the  midst  of  the  deluge  of 
ideas,  all  of  a  sudden  there  appears,  without  any  logical 
association,  one  idea  which  has  nothing  in  common  with 
the  preceding  fancies,  and  which  fixes  itself  with  desperate 
tenacity  and  constantly  recurs  amidst  the  others,  just  as 
in  concerted  music  the  theme  constantly  appears  among 
the  modulations  and  variations  surrounding  it. 

So  we  find  two  special  characteristics  of  the  first  stage 
of  intoxication  :  one  is  a  rapid  succession  and  the  other  a 
certain  fixity  of  ideas.  There  is  no  contradiction  between 
these  two  forms,  if  we  examine  carefully  the  mechanism 
of  the  intelligence. 

In  the  normal  state  all  the  faculties,  imagination,  memory, 
judgment,  the  association  of  ideas,  are  governed  by 
another  superior  faculty,  the  attention.  Attention,  or  the 
will,  is  the  man  himself.  It  is  the  individuality  which, 
being  in  full  possession  of  resources  which  it  controls, 
uses  them  when  and  where  it  wills.  Now,  even  in  the 
beginning  of  intoxication,  the  will  and  attention  disappear. 
There  is  little  more  than  imagination  and  memory  left, 
which,  abandoned  to  themselves  without  guidance  and 
control,  produce  the  most  unexpected  results.  Sometimes 
there  is  one  idea  that  cannot  be  driven  away,  some- 
times another  that  cannot  be  retained,  for  attention  is 
as  effective  for  the  elimination  of  certain  ideas  as  for  the 
fixation  of  others.  The  fixed  idea,  then,  may  depend  on 
the  absence  of  attention  fully  as  much  as  the  too  fleeting 
fancy,  and  in  both  cases  it  is  the  direct  result  of  poisoning 
of  the  brain  by  alcoholized  blood.  Therefore,  although 
in  the  first  stage  of  intoxication  it  may  seem  that  one's 
ability  for  work  is  increased,  he  will  soon  find,  if  he  really 
wishes  to  work,  that  he  is  unable  to  collect  and  fix  his 
ideas,  and  the  delusive  fertility  with  which  he  thinks 
himself  endowed  will  very  soon  appear  to  him  like  an 
actual    impotence    against    which     he    cannot    struggle. 


ALCOHOL,    CHLOROFORM,    HASCHISCH,    AND    COFFEE.     149 

Sometimes,  however,  by  chance  or  from  habit,  the  idea 
that  is  involuntarily  fixed,  is  precisely  the  one  he  wishes  to 
elaborate,  and  this  fortunate  coincidence  may  convince 
him  that  his  attention  is  intact.  But  this  will  prove  to  be 
an  illusion,  for  it  will  be  impossible  for  him  to  do  any 
other  work.  It  is  this  loss  of  attention,  then,  and  the  sur- 
excitation of  the  imagination  as  well  as  the  diminution  of 
judgment,  that  characterize  the  first  effects  of  intoxication. 
There  are  some  men,  however,  who  cannot  be  made  tipsy. 
After  a  great  quantity  of  alcohol  has  been  taken  they 
will  finally  have  all  the  symptoms  of  profound  intoxication, 
but  they  will  not  have  had,  in  appearance  at  least,  that 
period  of  intellectual  excitation  that  characterizes  the  first 
moments  of  intoxication.  This  peculiar  phenomenon  is  due 
to  the  influence  of  the  will.  In  these  cases  will  and  atten- 
tion, although  diminished,  have  not  entirely  disappeared, 
and  the  will  is  even  concentrated  on  the  fear  of  intoxi- 
cation. Thanks  to  this  fixed  idea,  which  the  intoxication 
exaggerates  still  more  in  intensity,  there  is  no  external 
manifestation  of  delirium.  Although  the  psychological 
effects  of  alcohol  may  be  felt,  there  is  yet  power  enough  in 
the  will  to  restrain  its  exhibition  to  others.  When,  on  the 
contrary,  they  abandon  the  will-power  by  giving  loose 
rein  to  all  the  ridiculous  fancies  that  occur  to  the  mind, 
they  are  then  no  longer  able  to  leave  off,  and  it  will  require 
a  grave  emergency  to  put  a  stop  to  the  hyper-ideation  and 
the  overflowing  speech.  If  one  refuses  to  act  upon  the 
first  development  of  ideas,  by  so  much  he  remains  master 
of  himself  so  far  as  his  tongue  and  his  acts  are  concerned. 
It  is  characteristic  of  those  who  consent  to  become  tipsy, 
who  say  to  themselves  at  the  beginning  of  a  dinner,  '  we 
will  be  free  and  easy,'  that  with  the  very  first  glasses  they 
are  drunk.  Sometimes  the  intention  is  equivalent  to  the 
act  itself,  and  one  may  become  drunk  without  drinking. 
This  effect  may  be  produced  by  good  news,  unexpected 
fortune,  unhoped-for  success,  producing  results  analogous 
to  intoxication,  so  that  in  common  parlance  we  say  such  a 
11 


150  TOISONS   OF   THE   INTELLIGENCE. 

one  is  '  drunk  with  success.'  This  moral  intoxication, 
which  closely  resembles  the  sur-excitation  of  alcohol,  is, 
however,  rarely  observed.  There  are  certain  persons 
whose  nervous  temperament  is  delicate  and  excitable. 
They  are  nervous  so  far  as  the  brain  is  concerned.  The 
slightest  accident  upsets  their  judgment,  the  smallest 
emotion  or  least  annoyance  destroys  at  once  their  presence 
of  mind  and  courage.  In  their  normal  state  they  lack 
neither  judgment  nor  will-power  ;  but  let  an  unforeseen 
accident  happen  and  they  lose  their  heads,  and  their  con- 
dition is  equivalent  to  that  produced  by  intoxication.  In 
such  persons  the  slightest  access  of  fever  brings  delirium. 
They  are  weak-headed,  and  unless  they  are  careful  they 
may  become  intoxicated  with  deplorable  facility.  This 
predisposition  resembles  hysteria. 

Besides  the  predisposition  of  the  individual,  there  are 
other  things  which  modify  the  effects  of  alcohol.  There 
is  a  difference  relatively  between  the  rapidity  with  which 
various  liquors  affect  the  intelligence. 

The  intoxication  of  brandy  is  dull  and  heavy.  It  pro- 
duces scarcely  any  intellectual  excitation,  and  seems  at 
first  to  act  upon  the  organic  functions  of  circulation  and 
respiration.  The  intoxication  of  wine,  however,  is  light 
and  stimulating,  particularly  Champagne  and  Burgundy, 
which  are  noted  for  their  psychic  effects.  The  mixture  of 
liquors  seems  to  increase  the  intensity  of  their  action  to  a 
great  degree. 

The  rapidity  of  alcoholic  absorption  is  a  matter  of  im- 
portance. When  one  is  fasting,  alcohol  acts  very  quickly  ; 
after  a  hearty  meal  it  is  absorbed  more  slowly.  A  queer 
custom  is  said  to  have  prevailed  among  the  heavy  drinkers 
of  England  in  former  times,  and  this  consisted  in  drinking 
a  glass  of  oil  at  the  beginning  of  dinner  and  thus  prevent- 
ing the  absorption  of  alcohol  by  the  stomach  and  intes- 
tines. Physiological,  but  disgusting.  Intense  heat  seems 
to  be  effective  in  rendering  liquors  more  intoxicating  than 
usual.     In   Egypt,  I   found  a  slight  quantity  of  Bordeaux 


ALCOHOL,    CHLOROFORM,    HASCHISCH,   AND   COFFEE.      1 5 1 

wine  and  water  too  stimulating  to  be  used  without  great 
care.  The  sudden  effect  of  cold,  by  checking  the  excre- 
tion of  alcohol  through  the  lungs  and  the  perspiration, 
may  produce  immediate  intoxication  in  those  who  have 
taken  alcoholic  drinks.  Hence  the  monks  of  St.  Bernard, 
according  to  Dr.  Burrill,  give  only  coffee  to  travellers. 

It  appears  then  that  a  small  dose  of  alcohol  sur-excites 
certain  intellectual  faculties,  while  it  paralyzes  others,  but 
if  the  dose  be  repeated  or  if  the  amount  is  sufficient  in  the 
first  instance,  there  may  be  a  total  disappearance  of  all 
trace  of  the  intelligence.  The  person  is  dead-drunk.  There 
is  complete  anaesthesia,  a  true  coma.  Now  between  these 
two  periods  of  sur-excitation  and  coma  occasionally  there 
occurs  a  very  serious  condition  which  the  ancient  authors 
called  "  convulsive  intoxication."  The  man  is  mad,  a  per- 
fect maniac  in  appearance  and  action,  dangerous  to  him- 
self and  to  others.  No  frenzy  can  be  more  ferocious  or 
appalling.  It  is  to  this  period  that  the  crimes  and  murders 
belong  that  are  committed  by  drunkards.  It  occurs  only 
in  those  whose  blood  is  vitiated  by  previous  alcoholic  ex- 
cesses, and  this  furious  delirium  may  come  after  a  new 
excess  in  drink  that  is  relatively  less  than  those  that  have 
preceded  it. 

There  is  another  form,  the  chronic  intoxication,  which 
profoundly  disturbs  the  functions  of  the  organs,  and  ends 
by  altering  their  tissues.  The  nervous  system,  and  more 
particularly  the  brainr  is  altered  more  perhaps  than  other 
organs.  In  the  case  of  dogs  whose  food  has  been  mixed 
with  alcohol,  we  find  the  brain  has  absorbed  a  definite 
amount  of  alcohol,  which  may  be  recovered  by  distillation. 
If  they  are  fed  in  this  way  for  a  long  time,  they  become 
restless  and  melancholy,  and  end  by  losing  their  senses. 
According  to  M.  Magnan,  they  have  hallucinations  ;  think- 
ing themselves  pursued,  they  run  off  affrighted,  howling 
and  snapping  at  the  empty  air. 

In  man,  likewise,  melancholy  and  fear  are  the  results  of 
chronic  poisoning  by  alcohol.      By  a  legitimate  penalty, 


152  POISONS   OF   THE   INTELLIGENCE. 

Nature  makes  expiation  for  the  joys  of  intoxication  by  the 
terrors  of  alcoholism.  At  first  there  is  only  a  vague  sense 
of  melancholy  which  they  seek  to  combat  with  new  doses 
of  the  poison.  Little  by  little  this  melancholy  increases. 
At  night,  while  half  asleep,  phantoms,  ill-defined  but  repul- 
sive, may  appear.  These  are  merely  illusions,  not  yet  so 
vivid  as  to  be  called  hallucinations.  But  soon  the  halluci- 
nations come,  hideous  forms  and  frightful  creations  of  a 
diseased  brain.  This  form  of  delirium  is  amply  illustrated 
in  medical  literature.  Sometimes  these  hallucinations  are 
so  frightfully  appalling  that  they  compel  the  unfortunate 
victim  to  suicide.  According  to  Brierre  de  Boisemont,  in 
a  total  of  4,595  cases  of  suicide,  530,  or  about  one-ninth, 
were  attributed  to  alcohol.  Poverty  and  drunkenness  are 
in  all  countries  associated,  and  we  must  attribute  the  use 
of  alcohol  by  those  who  are  constantly  struggling  against 
hunger  and  cold  as  due  to  an  instinctive  desire  for  forget- 
fulness  of  past  and  present  evils,  a  wish  to  blunt  the  sensi- 
bilities. It  is,  therefore,  among  the  poor,  and  especially  in 
cold  climates  where  poverty  is  harder  to  endure,  that 
alcoholism  makes  its  greatest  ravages.  In  England, 
among  a  million  paupers  helped  by  public  charities  in 
1865,  there  were  800,000  drunkards.  Whiskey  and  gin 
were  the  most  common  drinks,  together  with  porter,  ale, 
and  stout.  In  the  United  States,  where  the  thirst  for  alco- 
hol is  hardly  less  than  in  England,  besides  whiskey  and 
gin,  adulterated  brandy  and  rum  are  added  to  the  list.  In 
Sweden,  where  alcoholism  has  made  great  ravages,  accord- 
ing to  statistics,  each  inhabitant,  excluding  women  and 
children,  consumes  about  one  hundred  litres  (22.01  gallons) 
of  alcohol  annually.  In  Russia  the  consumption  is  enor- 
mous. They  use,  besides  the  spirits  of  grain,  such  as 
vodke  and  kummel,  brega  or  white  beer,  symorosli  or 
birch-wine,  and  a  great  number  of  other  alcoholic  drinks. 
The  Tartars  of  the  East  drink  fermented  mares'  milk,  a 
very  alcoholic  liquor  known  as  koumys. 

In  temperate  climates  and  in  the  south  of  Europe  drunk- 


ALCOHOL,    CHLOROFORM,    HASCHISCH,    AND   COFFEE.      1 53 

enness  is  a  rare  vice.  Finally,  excess  of  drink  destroys 
every  year  about  50,000  persons  in  England,  40,000  in 
Germany,  25,000  in  Russia,  4,000  in  Belgium,  and  2,000  in 
France.  People  reduced  to  servitude,  or  who  have  emi- 
grated in  order  to  support  themselves,  are  rarely  sober. 
The  Irish  and  Poles  are  examples  of  this.  The  Chinese  in 
their  own  country  are  a  very  sober  people,  but  when  they 
go  abroad  they  become  desperate  drunkards. 

Savages  brought  in  contact  with  advancing  civilization 
invariably  borrow  its  most  vicious  features,  and  acquire  at 
once  the  habit  of  intoxication. 

Among  the  alcoholic  poisons  we  have  not  yet  mentioned 
absinthe.  In  fact,  absinthe  does  not  act  solely  by  means 
of  the  alcohol  it  contains,  but  rather  by  the  essence  of 
absinthe,  which  even  in  a  small  dose  is  a  notable  poison. 
There  is  this  difference  between  absinthe  and  alcohol,  that 
instead  of  acting  solely  on  the  encephalic  nervous  system, 
absinthe  also  acts  with  great  rapidity  upon  the  spinal 
cord,  producing  tremors,  paroxysms  of  epileptiform  con- 
vulsions, and  finally  attacks  of  true  epilepsy.  The  sur- 
excitation of  absinthe  is  also  more  marked  than  that  of 
alcohol.  In  every  case  it  is  an  energetic  poison,  and  its 
prolonged  use  is  far  more  injurious  to  the  intelligence  than 
that  of  alcohol,  as  has  been  shown  by  the  researches  of  M. 
Magnan. 

Alcohol  is  an  excellent  stimulant,  and  in  moderate  doses 
is  useful  as  well  as  agreeable.  Its  effect  upon  the  nutritive 
process  is  well  known,  and  its  tonic  action  is  incontest- 
able. But  how  feeble  are  its  advantages  contrasted  with 
its  evils  ! 

III. 

CHLOROFORM. 

Chloroform  should  be  classed  with  alcohol.  Physiologi- 
cally the  action  of  these  two  poisons  is  nearly  the  same, 
and  although  their  employment  is  different,  their  function 
is  nearly  identical. 


154  POISONS   OF   THE   INTELLIGENCE. 

The  principal  action  of  chloroform  is  the  paralysis  of 
sensation,  or  anaesthesia.  This  means  that  it  acts  upon  the 
intelligence,  for  sensation  is  only  one  of  the  forms  of  intel- 
ligence.    This  point,  however,  needs  some  explanation. 

Two  grand  functions  are  vested  in  the  nervous  system, 
sensation  and  movement.  It  is  by  sensation  that  we 
receive  impressions  that  come  from  without  ;  it  is  by  the 
excitation  of  the  muscles,  or  movement,  that  we  manifest 
our  will  and  act  upon  exterior  objects.  When  one  is 
neither  sick  nor  poisoned,  the  will  (that  is  to  say,  the  in- 
telligence) excites,  through  the  medium  of  the  spinal 
cord,  the  different  muscles,  and  produces  movement.  But 
this  condition  is  not  absolutely  necessary,  since,  in  decapi- 
tated animals,  for  instance,  the  nervous  system  of  the 
spinal  cord  may  still  excite  muscular  movements.  There 
is  motility,  but  no  sensation.  There  is  sensation  only  when 
the  intelligence  is  intact  and  capable  of  perception  ;  there- 
fore, when  there  is  no  intelligence  there  can  be  no  sensation. 
This  is  supported  by  pathological  observations.  When- 
ever the  intelligence  is  attacked,  there  are  at  the  same 
time  disorders  of  sensation,  and  reciprocally.  So  when 
we  see  a  patient  presenting  notable  troubles  of  sensation, 
the  nerves  being  intact,  there  must  be  a  lesion  of  the  cen- 
tral nervous  system,  and  a  lesion  which  does  not  leave 
the  intelligence  unaffected. 

Anatomy  and  comparative  physiology  are  in  accord 
with  pathology.  Some  animals  have  very  little  percep- 
tion ;  they  -are  the  inferior  animals,  their  intelligence  is 
obscure,  and  their  sensation  is  as  obtuse  as  their  intelli- 
gence. But  in  proportion  as  we  consider  the  more  intelli- 
gent animals,  we  see  sensation  becoming  more  and  more 
delicate,  until  in  man,  the  most  intelligent  of  all,  sensation 
is  the  most  perfect.  So  among  the  different  races  those 
are  the  most  intelligent  who  are  the  most  sensitive.  The 
anatomical  arrangement  of  the  nervous  centres  is  in  accor- 
dance with  this  coincidence.  In  man  the  posterior  columns 
of  the  spinal  cord  are  more  voluminous  than  the  anterior 


ALCOHOL,    CHLOROFORM,    HASCHISCH,   AND    COFFEE.      1 55 

columns.  Now  the  anterior  columns  transmit  the  motor 
excitations  to  the  nerves,  while  the  posterior  columns 
serve  for  the  conduction  of  sensitive  excitations.  In  like 
manner  the  posterior  lobes  of  the  brain,  compared  with 
those  of  animals,  are  relatively  more  developed  in  man 
than  the  anterior  lobes.  It  is  in  the  posterior  lobes  that 
the  perception  of  sensitive  excitations,  or  the  faculty  of 
sensation,  appears  to  reside. 

Whatever  may  be  the  spontaneous  development  of  the 
mind  itself  through  the  proper  constitution  of  its  organ 
the  brain,  all  our  knowledge  comes  from  our  sensations  and 
from  the  brain-work  depending  on  them.  Intelligence  is 
in  some  sort  the  product  of  these  two  factors. 

Poisons  which  act  upon  the  intelligence  are,  therefore, 
poisons  of  sensation,  and  in  this  respect  alcohol  does  not 
differ  from  chloroform.  In  the  beginning  of  intoxication 
there  is  already  a  marked  insensibility,  but  in  the  coma- 
tose period  insensibility  is  absolute,  just  as  in  the  last 
period  of  chloroform  poisoning  ;  so  that  chloroform  intoxi- 
cation follows  a  march  parallel  to  that  of  alcohol,  and  we 
may  distinguish  a  first  period  of  chloroform  intoxication 
and  a  second  period  of  sleep  or  coma. 

When  one  inhales  chloroform,  the  first  whiffs  make  him 
giddy  and  create  a  very  disagreeable  sensation  of  vertigo 
and  bewilderment.  This  vertigo  augments,  and  in  pro- 
portion as  the  patient  continues  to  inhale  the  toxic  sub- 
stance his  ideas  become  exalted.  He  understands  and 
responds  to  all  that  is  said,  but  his  replies  are  like  one 
intoxicated;  his  impressions  are  exaggerated,  his  judgment 
is  gone,  and  he  gives  a  theatrical  accent  to  the  most  insig- 
nificant responses,  producing  a  grotesque  effect.  The 
ideas  become  more  and  more  confused,  will  and  judgment 
are  abolished,  imagination  becomes  disordered  and  delir- 
ious, in  a  word,  it  is  a  condition  of  sleep  with  dreams,  nearly 
analogous  to  that  which  occurs  in  ordinary  sleep. 

Attention,  judgment,  the  will,  and  memory  disappear  at 
the  same  time,  so  that  we  may  see  the  peculiar  spectacle 


156  POISONS   OF  THE   INTELLIGENCE. 

of  a  person  living  and  thinking,  but  whose  life  and  thought 
leave  no  trace  on  his  memory.  When  we  tell  him  what 
he  said  or  did,  it  will  be  news  to  him.  There  will  have 
been  a  lapse  in  the  memory  of  his  intellectual  operations, 
but  not  in  their  occurrence.  It  is  the  memory  and  not  the 
conception  of  ideas  that  the  poison  has  affected. 

There  should  be  two  distinct  faculties  recognized  in  that 
which  constitutes  memory.  For  instance,  one  who  is 
drunk  enough  to  stagger  home  may  remember  the  street, 
the  house,  and  even  the  room  where  he  lives.  But  the 
next  morning  he  can  remember  nothing  that  occurred  since 
he  was  drinking  in  the  evening.  How  he  got  home  is  a 
mystery  to  him,  and  there  is  a  void  in  his  memory.  Yet 
his  memory  was  sufficient  to  enable  him  to  find  his  way. 
There  are,  then,  two  kinds  of  memory,  which  we  will  call 
active  and  passive.  The  first  is  only  possible  when  the 
intellectual  faculties,  including  the  will  and  attention,  are 
intact.  There  must  be  power  to  direct  the  attention,  and 
this  power  is  absent  in  chloroform  and  alcoholic  intoxica- 
tion. Then,  when  poisons  of  the  intelligence  destroy  the 
memory,  they  only  alter  the  active,  reflecting,  conscious 
memory  ;  their  action  is  not  exerted  on  the  memory  of 
past  events  (habit-memory),  those  are  ineffaceable  except 
by  a  profound  lesion  of  the  nervous  centres.  When  chloro- 
form passes  into  the  blood  through  the  pulmonary  mucous 
membrane,  active  memory,  which  requires  the  will  and 
attention,  disappears,  although  the  intelligence  is  not  yet 
destroyed.  Ideas  are  still  conceived,  old  memories  persist 
sometimes  the  recollection  of  past  events  is  strangelytsur-ex- 
cited.  Forgotten  languages  return,  old  events  long  buried 
in  oblivion  come  back.  This  sur-excitation  of  the  memory 
is  a  peculiarity  sometimes  met  with  in  some  forms  of 
insanity  where  there  is  a  coincident  loss  of  active  memory. 

Chloroform-insensibility  occurs  very  promptly,  but  it 
generally  occurs  only  after  the  loss  of  the  memory  ;  and 
this  loss  of  memory  first,  and  sensation  afterwards  is  very 
peculiar. 


ALCOHOL,    CHLOROFORM,    HASCHISCH,   AND    COFFEE.      1 57 

So  when  an  operation  is  begun  before  insensibility  is 
complete,  the  patient  will  shriek  and  struggle  as  though  he 
suffered,  and  cry  out  that  the  operation  has  begun  too 
soon.  Yet,  on  awakening,  he  remembers  nothing  of  what 
has  occurred.  The  question  arises — Ts  a  pain  that  leaves 
no  trace  in  the  mind  or  memory  a  true  pain  ?  It  is  diffi- 
cult to  answer,  but  we  may  assume  that  to  suppress  the 
prolonged  consciousness  of  pain,  is  equivalent  to  suppress- 
ing the  pain  itself.  A  pain  without  memory  is  not  a  true 
pain,  since  it  lacks  that  which  is  the  precise  characteristic 
of  every  painful  impression,  that  prolonged  sentiment  which 
disturbs  the  mind,  and  the  memory  of  which,  whenever  it 
occurs,  is  a  feeble  image,  but  nevertheless  an  active  one, 
of  the  primitive  pain.  Two  persons  have  their  teeth  ex- 
tracted ;  one  with,  the  other  without  chloroform.  Both 
appear  to  suffer  alike  ;  both  cry  out  and  struggle.  But 
the  one  who  has  taken  the  chloroform  remembers  nothing 
of  the  pain,  while  the  other,  in  imagination  or  memory, 
will  suffer  the  operation  over  and  «over  again. 

When  chloroform  is  given,  a  great  deal  depends  on  the 
disposition  of  the  patient.  If  he  is  couragous  and  resolute, 
there  will  be  no  difficulty  in  producing  insensibility  ;  but 
if  he  is  filled  with  a  dread  of  the  operation,  it  is  necessary 
to  use  great  care  ;  for  we  have  noticed  in  such  cases  a 
greater  tendency  to  syncope.  Moreover,  he  will  resist  for 
a  long  time  the  action  of  the  chloroform,  so  that  more  will 
be  required  than  if  he  abandoned  himself  willingly  to  its 
effects.  Although  chloroform  is  irresistible,  yet  the  cere- 
bral excitation  permits  some  patients  to  resist  its  toxic  in- 
fluence with  a  will'that  is  exaggerated  in  strength.  This 
same  thing  has  its  analogue  in  alcoholic  intoxication.  The 
more  we  study  this  agent  the  clearer  it  becomes  that  there 
is  an  antagonism  between  the  different  intellectual  facul- 
ties, the  voluntary  and  the  involuntary  faculties.  The  con- 
ception of  ideas  goes  on  as  usual,  but  their  normal  correla- 
tion is  lost.  The  association  of  ideas  is  continuous,  and 
though  the  connection  be  disorderly  and  incongruous,  still 


158  POISONS   OF   THE   INTELLIGENCE. 

there  is  no  break  or  hiatus.  Exterior  sensations  still  occur 
and  bring  their  series  of  conceptions.  Hearing  is  the  last 
sense  to  disappear.  When  the  patient  can  neither  see  nor 
feel,  he  hears  what  is  said  around  him,  and  the  remarks  of 
the  bystanders  give  rise  in  his  brain  to  all  kinds  of  ideas. 

(Something  of  the  same  kind  occurs  in  the  natural  sleep 
of  children,  rarely  in  adults.  There  is  nearly  always  in 
children  a  certain  degree  of  natural  somnambulism.  The 
child  talks  aloud,  laughs  with  joy,  or  cries  from  fear.  The 
mother,  by  a  few  kind  words  and  caresses,  without  waking 
the  child,  can  change  the  direction  of  these  ideas,  and  quiet 
the  agitation  so  that  the  sleep  becomes  tranquil.  On  wak- 
ing, there  is  no  recollection  of  the  occurrence.)  But  all 
these  phenomena  which  testify  to  the  existence,  if  not  the 
integrity  of  the  intelligence,  do  not  delay  its  disappearance. 

The  groans,  cries  and  laughter,  are  succeeded  by  con- 
fused and  unintelligible  speech.  The  muscles  contract 
with  energy  under  the  influence  of  delirium,  they  relax 
slowly  and  end  by  becoming  inert.  To  the  period  of 
excitation  succeeds  the  period  during  which  there  is  pro- 
found sleep.  Whatever  may  have  been  the  violence  of  the 
delirium  or  the  severity  of  the  operation  which  is  per- 
formed, nothing  can  wake  the  patient  from  the  comatose 
state  in  which  he  is  plunged.  His  respiration  is  regular, 
the  pulse  is  soft  and  full,  the  pupils  are  immobile,  and  the 
features  like  one  paralyzed.  Intelligence  is  entirely  abol- 
ished. Nevertheless,  all  parts  of  the  cerebro-spinal  nervous 
system  are  not  paralyzed.  The  integrity  of  the  medulla 
oblongata  is  indicated  by  the  regular  movements  of  the 
heart  and  of  the  respiration,  although  the  other  parts  of 
the  spinal  cord  are  unable  to  accomplish  their  functions. 
It  is  to  this  integrity  of  the  medulla  oblongata  that  immu- 
nity from  danger  is  due.  It  is  therefore  necessary  to  keep 
a  constant  watch  of  the  pulse  and  of  the  respiration,  for  too 
strong  a  dose  of  chloroform  may  overwhelm  that  portion 
of  the  nervous  system  which  presides  over  the  movements 
of  organic  life.     As  to  the  spinal  cord,  it  becomes  affected 


ALCOHOL,    CHLOROFORM,    HASCHISCH,   AND   COFFEE.      1 59 

later  than  the  brain,  but  sooner  than  the  medulla  oblon- 
gata, so  that  these  three  regions  of  the  nervous  system, 
which  preside  over  three  different  functions,  appear  to  go 
under  the  influence  of  chloroform  singly  and  successively. 
Claude  Bernard  has  recently  demonstrated  that  the  brain 
is  paralyzed  before  the  spinal  cord,  so  that  sensation  is 
abolished,  while  motility  remains  intact.  He  has  shown, 
moreover,  that  the  brain  may  exercise  over  the  spinal 
cord  a  kind  of  paralyzing  action.  In  limiting  the  action  of 
chloroform  to  the  brain  by  a  section  of  the  spinal  cord,  we 
obtain  anaesthesia,  but  if  we  perform  a  reverse  operation, 
or,  in  other  words,  if  we  limit  the  action  of  chloroform  to 
the  spinal  cord,  in  preventing  the  encephalon  from  under- 
going the  action  of  the  poison,  anaesthesia  will  be  impossi- 
ble before  the  total  death  of  the  nervous  cellules.  (Con- 
firmed also  by  the  experiments  of  Liiys.)  Very  man)-  other 
volatile  and  toxic  substances  act  in  the  same  way  as  chloro- 
form and  may  be  used  instead  of  it,  but  chloroform  is  the 
type  of  all.  The  various  forms  of  ether  are  most  commonly 
known  and  used.  Certain  gases  have  analogous  properties, 
and  particularly  nitrous  oxide  or  laughing  gas,  which  is 
preferable  to  chloroform  in  dentistry  and  short  operations, 
because  the  anaesthesia  occurs  and  passes  off  rapidly. 

Recently  a  new  substance,  chloral,  has  been  introduced 
into  therapeutics,  which  resembles  chloroform  in  its  chem- 
ical constitution  and  in  some  of  its  physiological  properties. 
It  cannot  take  the  place  of  chloroform  in  producing  surgi- 
cal anaesthesia,  since  it  requires  enormous  doses  to  abolish 
all  trace  of  sensation,  but  it  is  a  valuable  hypnotic.  In  its 
power  to  produce  a  tranquil  sleep  and  to  allay  pain  it 
resembles  morphine  more  than  chloroform. 

IV. 

HASCHISCH. 

The  extract  of  Indian  hemp,  or  haschisch,  is  used  in  three 
forms  :  dawamesc,  a  nauseous  mixture  of  aromatics,  veget- 


IÔO  POISONS    OF   THE   INTELLIGENCE. 

able  oils  and  haschisch, taken  before  eating;  haschisch  that 
is  smoked  in  pipes  or  cigarettes,  the  true  oriental  style  ;  and 
the  aqueous  extract,  or  hafioun,  which  is  more  active  than 
the  other  preparations.  In  moderate  doses  the  effect  is 
very  agreeable  and  not  dangerous.  A  slight  disturbance 
of  digestion,  a  little  heaviness  of  the  head,  and  cerebral 
excitation  are  all  that  is  to  be  feared  from  ordinary  doses 
of  dawamesc  and  hafioun. 

Unless  anticipated,  the  first  effects  of  haschisch  may  pass 
unperceived.  These  consist  of  a  certain  motor  and  sensi- 
tive excitation  of  the  spinal  cord.  Twinges  are  felt  in  the 
neck,  back,  and  limbs,  and  chills  run  all  over  the  body. 
There  are  flashes  hot  and  cold  that  rise  to  the  head.  With 
all  this  there  is  a  certain  comfort  and  satisfaction,  like  that 
accompanying  a  slight  effect  of  alcohol.  Little  by  little 
the  excitation  of  the  spinal  cord  produces  more  character- 
istic effects.  They  become  uneasy,  walk  up  and  down, 
and  stretch  themselves  out  in  all  directions.  They  wish  to 
dance,  to  move  about,  to  lift  enormous  weights,  and  in  the 
midst  of  this  merely  muscular  excitement  the  mind  remains 
calm.  But  all  at  once,  by  a  chance  word  from  one  of  the 
bystanders,  by  some  perfectly  natural  remark,  they  are  set 
to  laughing.  The  laugh  is  involuntary,  unreasonable, 
prolonged,  nervous,  convulsive,  and  seems  interminable. 
When  this  burst  of  laughter  has  ceased,  they  know  that  it 
has  been  ridiculous  ;  they  regain  their  senses  and  under- 
stand that  this  laughter  was  one  of  the  first  effects  of  the 
poison. 

From  this  moment  the  ideas  become  more  and  more 
crowded.  It  is  like  a  perpetual  blaze  of  fireworks,  spar- 
kling in  all  directions.  One  idea  succeeds  another  with 
dazzling  rapidity.  Thoughts  come  and  go  in  apparent 
disorder,  but  in  reality  according  to  the  laws  that  govern 
the  association  of  ideas  and  impressions.  Their  speech  is 
agitated,  almost  furious;  they  are  astonished  to  see  that 
those  around  them  do  not  partake  of  the  same  delirium 
which   they   feel,  and    are   indignant   at   their   stupidity. 


ALCOHOL,    CHLOROFORM,    HACHISCH,   AND   COFFEE.      l6l 

They  cannot  express  the  thoughts  that  occur  to  them  ; 
language  is  not  rapid  enough  to  keep  pace  with  their 
ideas. 

Every  idea,  whatever  its  nature  may  be,  is  exaggerated, 
we  may  say  that  there  is  a  hypertrophy  of  the  ideas.  We 
are  moved  to  tears  by  what  we  should,  in  the  normal  state, 
consider  merely  annoying.  The  most  simple  things  be- 
come theatrical,  and  it  is  with  tragic  tones  that  we 
announce  that  it  is  late,  or  that  the  wind  blows.  All 
this  silly  trash  gives  an  infantile  joy  which  we  do  not  try 
to  hide.  We  pass  from  laughter  to  tears  without  any 
transition  period.  Self-esteem  is  also  exaggerated,  and  the 
man  who  has  taken  haschisch  has  become  so  superior  to 
other  men  that  he  is  filled  with  contempt  at  their  stupidity. 

There  is  also  a  complete  moral  transformation,  and  it  is 
to  be  noted  that  all  the  phenomena  resemble  those  of 
hysteria.  In  general,  hysterical  women  have  brilliant 
ideas,  they  are  intelligent,  the  imagination  is  lively  and 
fertile,  but,  however  elevated  their  intelligence  may  be,  it 
is  defective  for  two  principal  reasons,  the  exaggeration 
of  sentiment  and  the  absence  of  the  will.  This  double 
characteristic  is  found  also  in  haschisch.  In  both,  the  exag- 
geration of  sentiment  produces  immoderation,  whether 
of  joy  or  sorrow.  Their  self-conceit  is  such  that  the 
slightest  remark,  the  most  inoffensive  word,  wounds  and 
offends  them.  They  dramatize  life.  Simple,  ordinary 
existence  does  not  prevent  them  from  indulging  this  the- 
atrical tendency.  They  play  with  equal  success  either 
comedy  or  tragedy.  Without  the  slightest  occasion  for 
display,  they  surprise  every  one  by  the  suddenness,  the 
mobility,  and  the  intensity  of  their  dramatic  passion. 

The  impotence  of  the  will  is  very  remarkable  in  the 
hysterical.  They  have  no  control  of  themselves  or  their 
sentiments.  They  tell  all  that  comes  into  their  heads, 
giving  utterance  to  a  thought  as  soon  as  it  is  conceived, 
without  regard  to  the  consequences  of  their  language.  So, 
in  a  short  conversation  with  one  who  is  hysterical,  we  are 


IÔ2  POISONS   OF   THE   INTELLIGENCE. 

impressed  with  the  contradictions,  untruths,  and  extrava- 
gances of  thought,  since  the  judgment  and  will  do  not  in- 
tervene to  rectify  that  which  is  defective.  That  kind  of 
judgment-power  or  common-sense  which  enables  us  to 
determine  what  is  best  to  say  and  what  is  best  to  remain 
unsaid,  is  unknown  to  the  hysterical. 

The  same  condition  exists  in  the  person  who  has  taken 
haschisch.  It  comes  on  suddenly,  and  therefore  those  who 
have  partaken  of  the  poison  should  never  allow  themselves 
to  mix  in  company  while  under  its  effects,  lest  their  extrava- 
gant speech  and  actions  should  put  them  in  some  ridiculous 
position  that  will  not  be  understood  by  those  around  them. 
Yet  with  the  intoxication  of  haschisch  there  is  a  conscious- 
ness of  the  loss  of  will-power,  and,  unlike  the  condition  of 
those  under  the  effects  of  alcohol,  we  are  aware  that  we 
cannot  trust  ourselves.  There  seems  to  be  a  double  iden- 
tity, one  of  ourselves  is  drunk  with  the  poison,  the  other 
looks  on  and  sees  and  remembers  it  all.  This  conscious- 
ness of  our  condition  is  also  found  in  some  cases  of  insan- 
ity, for  it  is  not  uncommon  for  those  unfortunates  to  come 
to  the  asylum  and  request  to  be  shut  up  lest  they  should 
do  themselves  or  some  one  else  an  injury,  so  conscious 
are  they  of  their  condition. 

The  two  most  characteristic  phenomena  of  haschisch  in- 
toxication and  that  which  is  not  usually  found  in  other 
intoxications,  is  the  alteration  of  our  ideas  of  time  and  space. 
Time  appears  to  be  immeasurably  lengthened.  Between 
two  clearly  conceived  ideas  we  think  we  entertain  an  infi- 
nite number  of  others,  indistinct  and  incomplete,  of  which 
we  have  a  vague  impression,  but  whose  number  and  extent 
fill  us  with  admiration.  These  ideas  seem  innumerable, 
and  as  time  is  only  measured  by  the  recollection  of  ideas, 
time  appears  prodigiously  long.  As  when  one  is  awakened 
suddenly  by  the  fall  of  a  canopy  on  the  bed,  the  shock 
gives  rise  to  a  series  of  fancies  longer  to  recount  than  to 
conceive  of.  The  dreamer  sees  himself  transported  to  the 
top  of  a  mountain  surrounded  by  a  hostile  mob.     They 


ALCOHOL,    CHLOROFORM,    HASCHISCH,   AND   COFFEE.      163 

throw  him  from  the  summit  of  a  rock,  and,  after  a  descent 
that  seems  to  occupy  years,  he  falls  on  his  head  in  a  ravine. 
All  these  conceptions  have  occupied  scarcely  half  a  second, 
the  time  that  was  necessary  to  be  awakened  by  the  piece 
of  wood  that  falls.  So  we  may,  by  a  kind  of  psychological 
experiment,  produce  a  similar  illusion.  If  one  while  riding 
in  a  carriage  is  overtaken  by  drowsiness  which  he  tries  to 
resist,  he  will  open  and  shut  the  eyelids  at  frequent  inter- 
vals, and  the  distance  passed  over,  as  well  as  the  time  oc- 
cupied while  the  eyes  are  shut,  will  seem  enormously  long. 
There  is  no  need  of  actual  sleep  to  give  rise  to  this  illusion 
as  to  the  duration  of  time.  While  the  eyes  are  closed,  the 
road  we  are  on,  or  rather  the  time  occupied  in  passing 
over  it,  will  seem  interminable.  Even  one  who  is  familiar 
with  the  route,  and  knows  that  it  is  not  very  long,  will 
think  he  has  already  arrived,  and  each  time  he  opens  his 
eyes  there  will  be  a  new  deception.  In  fact,  when  we 
remain  so  self-concentrated,  without  seeing  or  hearing,  we 
only  have  a  very  imperfect  notion  of  real  time.  On  the 
contrary,  when  our  senses  are  awake  and  attentive,  they 
unceasingly  correct  the  impressions  founded  solely  on 
psychic  ideas.  We  only  know  very  imperfectly  the  ser. 
vices  which  at  each  instant  all  our  senses  perform  for  us, 
and  it  is  only  by  reflection  and  psychological  analysis  that 
we  can  hope  to  understand  them.  In  dreams  and  sleep  this 
illusion  as  to  the  duration  of  time  is  vague,  but  with  hasch- 
isch it  becomes  clearly  marked.  Just  as  astonishing  is 
the  illusion  which  makes  short  distances  appear  immense. 
It  is  not  found  in  other  kinds  of  intoxication,  and  I  can 
scarcely  give  a  rational  explanation  of  it.  Even  its  descrip- 
tion is  difficult.  The  illusion  makes  a  bridge  or  an  avenue 
appear  to  have  no  end,  they  stretch  out  to  unheard  of  and 
improbable  distances.  When  we  go  up-stairs  the  steps 
seem  as  high  as  the  clouds.  A  river,  whose  opposite  bank 
is  in  plain  sight,  seems  as  large  as  an  arm  of  the  sea. 

Besides  these  two  illusions  of  space  and  time,  which  are 
very  tenacious  and  last  often  for  more  than  twentv-four 


164  POISONS   OF   THE    INTELLIGENCE. 

hours,  there  are  others  equally  strange,  but  perhaps  not  so 
invariable  in  their  occurrence. 

There  is  a  remarkable  resemblance  between  the  illusions 
of  haschisch  and  the  systemic  delirium  of  the  insane.  In 
the  latter,  the  delirious  idea  has  some  real  point  of  depar- 
ture, a  sensation  or  external  impression.  This  is  used  as  a 
basis  for  conceptions,  and  by  a  sort  of  induction,  by  no 
means  illogical,  a  whole  system  of  errors  is  built  up.  So, 
from  the  occurrence  of  nausea  or  gastric  pain,  they  con- 
clude that  they  have  been  poisoned  and  that  we  wish  to 
kill  them,  and  all  the  reasoning  in  the  world  would  fail  to 
convince  them  of  their  error.  This  is  precisely  what  oc- 
curs in  haschisch  intoxication.  The  intelligence  is  entirely 
subordinate  to  the  imagination  and  this,  in  turn,  to  an  ab- 
normal excitation  of  the  senses.  In  our  ordinary  condition 
it  is  very  certain  that  exterior  impressions  transform  cer- 
tain ideas  and  awaken  others,  but  we  are  only  conscious 
of  just  what  we  choose  to  be  conscious  of;  the  attention 
and  the  will  eliminate  and  destroy  outside  impressions 
which  we  do  not  notice,  so  that  they  leave  no  trace  in  the 
intelligence.  These  two  faculties  cover  with  a  thick  veil 
all  this  unconscious  work,  and  in  the  midst  of  the  confused 
activity  of  intellectual  operations  the  mind  only  sees  what 
it  wishes  to  see.  Thus  we  can  appreciate  the  condition  of 
the  intelligence  in  haschisch  intoxication  when  the  will  and 
the  attention  no  longer  protect  the  mind  from  the  inroad 
of  every  impression. 

The  feature  which  distinguishes  intoxication  of  haschisch 
from  that  of  alcohol  is  that  the  memory  remains  intact. 
We  remember  with  astonishing  exactitude  all  we  have 
seen,  said,  and  done.  If  the  dose  of  the  poison  is  very 
large  however,  there  is  a  complete  loss  of  memory  and 
even  furious  delirium,  so  that  haschisch  has  its  dangers, 
although  I  do  not  know  that  any  fatal  case  has  been  re- 
ported in  Europe.  In  some  cases  the  delirium  lasts  for 
many  days  and  is  very  alarming.  In  the  East,  haschisch  is 
in  very  general  use.     Almost  always  it  is  smoked  in  large 


ALCOHOL,    CHLOROFORM,    HASCHISCH,    AND    COFFEE.     1 65 

pipes  which  arc  passed  around.  Its  smoke  is  very  agreea- 
ble, exhaling  a  peculiar  aromatic  odor.  The  effects  of  the 
smoke  of  haschisch  do  not  differ  essentially  from  those  pro- 
duced by  the  ingestion  of  the  substance,  but  are  com- 
monly milder  in  their  form. 


V. 
OPIUM. 

The  desiccated  juice  of  the  poppy,  called  opium,  and  its 
tincture,  laudanum,  have  similar  properties.  We  find 
however  that  opium  is  a  very  complex  body,  a  mixture  of 
many  substances  having  analogous  but  not  identical  prop- 
erties. 

Besides  narcotine  and  morphine,  chemists  have  dis- 
covered many  other  constituents,  such  as  codeine,  nar- 
ceine,  thebaine,  papaverine,  etc.,  all  of  which  enter  into  the 
composition  of  opium.  But  these  different  bases  do  not 
act  upon  the  organic  functions  in  the  same  way.  Thus  the 
soporific  powers  of  narcotine  are  very  slight,  and  two 
grammes  of  this  substance  may  be  taken  without  produc- 
ing sensible  results,  although  a  centigramme  of  morphine, 
a  dose  two  hundred  times  less  in  amount,  is  sufficient  to 
provoke  toxicological  effects.  Thebaine  does  not  produce 
sleep,  but  excites  in  animals  convulsions  resembling  those 
of  strychnine;  yet  morphine  in  a  similar  dose  brings  on 
a  profound  sleep.  Another  remarkable  action  of  the  alka- 
loids of  opium  is  the  fact  that  their  effects  upon  man  arc 
not  the  same  as  those  they  produce  in  animals.  Man  is 
peculiarly  sensitive  to  the  action  of  morphine,  although 
thebaine  produces  hardly  any  effect  on  his  nervous  sys- 
tem. On  the  other  hand,  animals  are  not  sensitive  to  the 
effects  of  even  a  very  large  close  of  morphine,  although 
thebaine  is,  for  them,  a  virulent  poison.  Two  grammes  of 
morphine  would  not  kill  a  dog,  but  ten  centigrammes  of 
thebaine  would  be  inevitably  fatal.  In  general  physiology, 
12 


1 66  POISONS   OF   THE    INTELLIGENCE. 

this  difference  of  resistance  to  poisonous  agents  is  not  yet 
explained.  We  know  that  belladonna  and  atropine,  so  poi- 
sonous to  man,  have  but  a  slight  effect  on  a  rabbit,  and 
that  a  dose  sufficient  to  kill  ten  robust  men  is  hardly  enough 
to  kill  a  rabbit. 

Morphine,  the  principal  and  most  energetic  substance 
contained  in  opium,  so  far  as  its  action  on  man  is  con- 
cerned, has  very  nearly  the  same  effect  as  crude  opium. 
In  medicine  we  prescribe  them  indifferently,  so  that  we 
may  comprehend  them  both  in  a  common  description. 

The  sleep-producing  power  of  opium  is  supposed  to  be 
derived  from  its  action  on  the  cerebral  circulation.  It  is 
not  yet  certain  that  this  is  the  true  cause,  but  it  is  the  result 
of  much  laborious  investigation. 

On  trephining  the  skull  and  inspecting  the  cerebral 
surface  in  animals,  we  find  that  the  aspect  varies  accord- 
ing to  the  size  and  condition  of  the  blood-vessels  which 
cover  the  brain.  Sometimes  the  surface  is  purple,  swollen, 
and  covered  with  a  network  of  dilated  blood-vessels,  this 
is  cerebral  congestion.  At  other  times  it  is  pale,  depressed, 
and  the  capillaries  can  hardly  be  distinguished,  there  is  a 
deficiency  of  blood  or  aneemia  of  the  brain.  Now,  it  is 
found  that  the  circulation  of  the  retina  of  the  eye  is  the 
image  of  the  cerebral  circulation,  so  that  when  the  brain 
is  congested,  the  eye  is  also  congested,  and  vice  versa.  This 
furnishes  a  method  of  diagnosis  by  means  of  the  ophthal. 
moscope,  but  there  is  another  way  of  judging  of  the  con- 
dition of  the  blood-vessels  of  the  eye.  The  circular  and 
contractile  opening  in  the  iris,  the  pupil,  which  contracts 
in  the  light  and  dilates  in  the  dark,  is  always  contracted 
when  the  brain  is  congested,  and  always  dilated  when  the 
brain  is  anaemic,  provided  the  observation  is  not  made  with 
the  patient  placed  in  a  dazzling  light,  nor  in  a  darkness  too 
profound. 

Then  we  might  suppose  that,  since  in  normal  sleep,  as  in 
the  sleep  produced  by  opium,  the  pupil  is  very  much  con- 
tracted, the  brain  is  in  a  state  of  congestion  in  both  cases, 


ALCOHOL,    CHLOROFORM,    HASCHISCH,   AND   COFFEE.      167 

and  that  sleep  is  the  consequence  of  this  cerebral  conges- 
tion. 

Unfortunately  this  theory  is  only  an  hypothesis,  and 
facts  prove  that  it  is  not  exact.  Many  physiologists,  Dur- 
ham and  Hammond  among  others,  have  shown  by  exper- 
iments that  during  sleep  there  is  anasmia  of  the  brain. 
According  to  them,  we  must  understand  that  the  afflux  of 
blood  to  an  organ  cannot  determine  a  quiescent  state  of 
the  organ,  and  all  physiological  functions  should  be  re- 
tarded by  the  diminution  of  the  circulation,  in  the  brain 
as  well  as  in  all  other  vascular  organs. 

So  we  are  unable,  in  spite  of  experiments,  to  arrive  at  a 
definite  conclusion  as  to  whether  opium  produces  conges- 
tion or  anasmia  of  the  brain. 

Opium-sleep  is  not  precisely  the  same  as  ordinary  sleep. 
About  half  an  hour  or  an  hour  after  having  taken  opium, 
we  feel  a  slight  excitation,  a  general  feeling  of  vivacity  and 
satisfaction,  which  is  soon  replaced  by  a  kind  of  somno- 
lence that  is  rather  a  condition  of  reverie  than  of  dreams. 
We  experience  a  certain  pleasure  in  permitting  ourselves 
to  be  overcome  by  the  gentle  torpor.  Ideas  become 
images  which  succeed  each  other  rapidly,  without  our 
wishing  to  make  an  effort  to  change  their  course.  So  long 
as  the  intoxication  is  not  profound,  this  effort  is  still  possi- 
ble. We  know  that  we  are  going  to  sleep,  but  that,  if  we 
choose,  we  can  overcome  the  drowsiness.  Little  by  little 
the  legs  grow  heavy,  the  arms  fall  inert,  and  the  heavy 
eyelids  cannot  be  kept  open.  We  dream,  we  wander,  and 
yet  we  do  not  sleep  ;  the  consciousness  of  the  exterior 
world  has  not  yet  disappeared.  The  noises  outside,  the 
tick  of  the  clock,  the  rumbling  of  carriages,  are  obscurely 
perceived.  Active,  conscious  individuality  does  not  exist  ; 
a  passive  condition  has  replaced  it.  Gradually  all  becomes 
more  vague,  the  ideas  are  lost  in  a  confused  mist,  and 
everything  seems  immaterial.  The  body  seems  to  have 
vanished,  and  only  thought  remains,  brilliant,  but  growing 
more  and  more  confused.     Then  all  exterior  impressions 


1 68  POISONS   OF   THE    INTELLIGENCE. 

disappear,  and  we  experience  either  febrile  agitation, 
delirium,  or,  more  commonly,  a  calm  and  tranquil  sleep. 
The  charm  of  this  condition  is  that  we  know  we  are  sleep- 
ing. The  sleep  is  intelligent  and  comprehends  itself.  The 
hours  pass  with  marvellous  rapidity,  and  in  the  morning 
when  opium  seems  to  have  spent  its  force,  but  in  reality 
preserves  it  in  full,  the  sleep  is  peculiarly  delightful.  The 
mind,  freed  from  all  terrestrial  bonds,  seems  to  reign  in  a 
world  of  tranquil  and  serene  thought.  This  intoxication 
is  wholly  psychic,  far  superior  to  that  of  alcohol  or  hasch- 
isch, for  while  hashish  gives  a  few  hours  of  lunacy,  opium 
gives  sleep,  which  is  far  better. 

One  should  have  suffered  from  insomnia  in  order  to 
appreciate  what  opium  can  do.  To  listen  while  all  the 
minutes  of  the  night  successively  pass  in  the  midst  of  an 
overwhelming  silence,  to  turn  and  toss  on  the  bed,  to 
sketch  the  outline  of  confused  ideas,  without  being  able 
to  grasp  a  single  one,  to  struggle  hopelessly  against  an 
unconquerable  restlessness,  this  is  torture  which  no  one 
can  comprehend  who  has  not  experienced  it.  The  power 
which  opium  possesses  to  give  a  calm  and  tranquil  sleep, 
to  assuage  pain,  and  to  control  the  febrile  agitation  in 
some  diseases,  renders  it  a  priceless  boon  to  the  patient 
and  a  remedy  of  wonderful  value  to  the  physician.  It  is 
not  merely  a  poison  of  the  intelligence,  it  exercises  also  an 
energetic  modifying  action  on  the  sensibility.  We  do  not 
know  whether  this  comes  from  its  action  on  the  nerve 
which  transmits  the  excitation,  or  on  the  brain  which  per- 
ceives it,  but  without  causing  sleep  it  still  has  the  power 
of  calming  nervous  excitation  and  hyperesthesia.  When 
it  quiets  hyperesthesia  it  does  not  procure  sleep,  for  all 
its  force  seems  to  be  exerted  against  the  pain,  and  there  is 
not  enough  action  to  carry  its  effect  so  far  as  to  induce 
sleep.  Those  who  take  opium  to  allay  inveterate  neural- 
gia, are  obliged  to  increase  the  dose  to  a  great  extent 
before  they  can  obtain  its  narcotic  action. 

There  is  in  one  respect  a  strong  contrast  between  opium 


ALCOHOL,   CHLOROFORM,    HASCHISCH,   AND   COFFEE.     1 69 

and  alcohol,  for  alcohol  has  a  cumulative  effect;  the  more 
one  drinks  the  more  easily  they  become  intoxicated,  but 
with  opium  the  system  will  become  accustomed  to  the 
poison,  so  that  increased  doses  will  be  necessary  to  pro- 
duce the  effects  at  first  obtained  by  moderate  doses. 
When  one  has  become  habituated  to  the  use  of  opium,  it 
becomes  a  necessary  stimulant,  and  he  becomes  just  as 
sick  from  an  absence  of  the  poison  as  from  its  excess.  So 
if  by  chance  we  diminish  the  dose  or  forget  to  give  it,  such 
patients  are  seized  with  sudden  attacks  of  pain,  whose  ori- 
gin is  easily  traced  to  the  absence  of  the  stimulant  to 
which  the  system  has  been  accustomed. 

Opium  is  a  dangerous  poison,  not  merely  from  the  fatal 
effects  of  an  overdose,  but  because  its  use  is  apt  to  lead  to 
the  opium  habit.  In  China  this  is  a  national  vice  ;  and  the 
opium-shops,  where  opium  is  smoked,  correspond  to  the 
cabarets  and  taverns  of  more  civilized  lands.  Travellers 
tell  us  that  opium-smokers  who  daily  indulge  in  this  ex- 
cess fall  at  last  to  the  lowest  depths  of  degradation,  moral 
and  physical.  Pale,  haggard,  and  emaciated,  scarcely  able 
to  drag  themselves  around,  they  can  only  arouse  a  little 
energy  when  a  new  dose  of  the  poison  stimulates  them. 

VI. 
COFFEE. 

Opium  has  an  antidote,  so  that  while  we  are  able  produce 
sleep,  we  are  also  able  to  produce  insomnia.  The  effects 
of  coffee  on  the  intellect  are  diametrically  opposed  to  those 
of  opium.  Its  action  is  well  known,  because  it  is  in  com- 
mon use.  Some  use  it  as  a  necessary  stimulant  to  intel- 
lectual work.  In  others  this  excitation  is  manifested  by  a 
painful  insomnia.  For  them,  coffee  is  a  veritable  poison 
that  deprives  them  of  the  most  precious  of  boons.  In  some 
cases,  when  they  have  taken  too  strong  a  dose,  a  most  dis- 
tressing condition  of  anxiety  and  restlessness  comes  on, 
wholly  different  from  the  quiet  activity  of  opium.     With 


I70  POISONS    OF    THE    INTELLIGENCE. 

coffee  the  imagination  is  scarcely  excited,  but  the  will 
seems  to  be  stimulated.  We  wish  to  walk  quickly,  we 
cannot  keep  quiet  long  enough  to  finish  any  task.  With 
opium,  alcohol,  and  haschisch  we  feel  that  there  is  a  kind  of 
drowsiness  of  the  attention,  but  with  coffee  the  attention 
and  memory  are  perpetually  on  the  alert.  It  gives,  there- 
fore, a  veritable  intoxication  which  is  much  more  fatiguing 
than  the  somnolent  intoxication  of  opium,  but  it  leads  to 
the  same  result.  In  wishing  to  do  too  much,  the  mind  does 
too  little.  By  this  over-excitement  the  will  is  injured,  and 
the  perfect  balance  of  the  intellectual  faculties  is  destroyed 
as  much  by  excess  as  by  inactivity  of  the  will. 

We  say  generally  that  coffee  produces  anaemia  of  the 
brain,  while  opium  and  alcohol  cause  congestion,  but  this 
physiological  theory  is  far  from  being  established  on  a 
sure  foundation,  and  new  experiments  are  necessary. 
Nevertheless,  we  know  very  exactly  the  rôle  played  by 
coffee  in  general  nutrition.  It  delays  organic  combustion 
and  economizes  food.  In  the  normal  state  an  infinite  num- 
ber of  chemical  actions  are  carried  on  in  the  system  whose 
final  results  are  the  production  of  heat  and  the  liberation 
of  carbonic  acid.  The  carbonic  acid  passes  into  the  venous 
blood  from  which  it  is  eliminated  by  the  lungs.  The  quan- 
tity of  carbonic  acid,  then,  may  in  a  measure  be  regarded 
as  an  indication  of  the  activity  of  nutrition.  Now  with 
coffee,  we  find  that  the  quantity  of  carbonic  acid  is  dimin- 
ished without  any  diminution  of  the  vital  forces,  and  this 
occurs  without  any  change  in  food,  work,  or  functional 
activity.  Instances  might  be  given  of  the  use  often  made 
of  coffee,  to  enable  workmen  to  continue  laborious  tasks 
with  little  food.  It  therefore  moderates  the  activity  of  the 
chemical  processes  and  prevents  the  waste  of  tissue.  Other 
substances  have  analogous  properties,  especially  tea  and 
cocoa.  It  is  probable  that  caffeine,  théine,  and  cocaine 
are  analogous  chemically  and  physiologically,  and  that 
their  effects  on  the  intellectual  functions  are  very  nearly 
identical. 


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QP381 


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Richet 

.Physiology  and   histology  of   the 
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